Add the ability to pin Issues (#24406)

This adds the ability to pin important Issues and Pull Requests. You can
also move pinned Issues around to change their Position. Resolves #2175.

## Screenshots

![grafik](https://user-images.githubusercontent.com/15185051/235123207-0aa39869-bb48-45c3-abe2-ba1e836046ec.png)

![grafik](https://user-images.githubusercontent.com/15185051/235123297-152a16ea-a857-451d-9a42-61f2cd54dd75.png)

![grafik](https://user-images.githubusercontent.com/15185051/235640782-cbfe25ec-6254-479a-a3de-133e585d7a2d.png)

The Design was mostly copied from the Projects Board.

## Implementation
This uses a new `pin_order` Column in the `issue` table. If the value is
set to 0, the Issue is not pinned. If it's set to a bigger value, the
value is the Position. 1 means it's the first pinned Issue, 2 means it's
the second one etc. This is dived into Issues and Pull requests for each
Repo.

## TODO
- [x] You can currently pin as many Issues as you want. Maybe we should
add a Limit, which is configurable. GitHub uses 3, but I prefer 6, as
this is better for bigger Projects, but I'm open for suggestions.
- [x] Pin and Unpin events need to be added to the Issue history.
- [x] Tests
- [x] Migration

**The feature itself is currently fully working, so tester who may find
weird edge cases are very welcome!**

---------

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Giteabot <teabot@gitea.io>

1 files changed, 268 insertions, 0 deletions

diff --git a/templates/swagger/v1_json.tmpl b/templates/swagger/v1_json.tmpl
index 03a65184c3..15043e465f 100644
--- a/templates/swagger/v1_json.tmpl
+++ b/templates/swagger/v1_json.tmpl
@@ -6191,6 +6191,39 @@
         }
       }
     },
+    "/repos/{owner}/{repo}/issues/pinned": {
+      "get": {
+        "produces": [
+          "application/json"
+        ],
+        "tags": [
+          "repository"
+        ],
+        "summary": "List a repo's pinned issues",
+        "operationId": "repoListPinnedIssues",
+        "parameters": [
+          {
+            "type": "string",
+            "description": "owner of the repo",
+            "name": "owner",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "string",
+            "description": "name of the repo",
+            "name": "repo",
+            "in": "path",
+            "required": true
+          }
+        ],
+        "responses": {
+          "200": {
+            "$ref": "#/responses/IssueList"
+          }
+        }
+      }
+    },
     "/repos/{owner}/{repo}/issues/{index}": {
       "get": {
         "produces": [
@@ -7419,6 +7452,144 @@
         }
       }
     },
+    "/repos/{owner}/{repo}/issues/{index}/pin": {
+      "post": {
+        "tags": [
+          "issue"
+        ],
+        "summary": "Pin an Issue",
+        "operationId": "pinIssue",
+        "parameters": [
+          {
+            "type": "string",
+            "description": "owner of the repo",
+            "name": "owner",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "string",
+            "description": "name of the repo",
+            "name": "repo",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "integer",
+            "format": "int64",
+            "description": "index of issue to pin",
+            "name": "index",
+            "in": "path",
+            "required": true
+          }
+        ],
+        "responses": {
+          "204": {
+            "$ref": "#/responses/empty"
+          },
+          "403": {
+            "$ref": "#/responses/forbidden"
+          },
+          "404": {
+            "$ref": "#/responses/notFound"
+          }
+        }
+      },
+      "delete": {
+        "tags": [
+          "issue"
+        ],
+        "summary": "Unpin an Issue",
+        "operationId": "unpinIssue",
+        "parameters": [
+          {
+            "type": "string",
+            "description": "owner of the repo",
+            "name": "owner",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "string",
+            "description": "name of the repo",
+            "name": "repo",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "integer",
+            "format": "int64",
+            "description": "index of issue to unpin",
+            "name": "index",
+            "in": "path",
+            "required": true
+          }
+        ],
+        "responses": {
+          "204": {
+            "$ref": "#/responses/empty"
+          },
+          "403": {
+            "$ref": "#/responses/forbidden"
+          },
+          "404": {
+            "$ref": "#/responses/notFound"
+          }
+        }
+      }
+    },
+    "/repos/{owner}/{repo}/issues/{index}/pin/{position}": {
+      "patch": {
+        "tags": [
+          "issue"
+        ],
+        "summary": "Moves the Pin to the given Position",
+        "operationId": "moveIssuePin",
+        "parameters": [
+          {
+            "type": "string",
+            "description": "owner of the repo",
+            "name": "owner",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "string",
+            "description": "name of the repo",
+            "name": "repo",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "integer",
+            "format": "int64",
+            "description": "index of issue",
+            "name": "index",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "integer",
+            "format": "int64",
+            "description": "the new position",
+            "name": "position",
+            "in": "path",
+            "required": true
+          }
+        ],
+        "responses": {
+          "204": {
+            "$ref": "#/responses/empty"
+          },
+          "403": {
+            "$ref": "#/responses/forbidden"
+          },
+          "404": {
+            "$ref": "#/responses/notFound"
+          }
+        }
+      }
+    },
     "/repos/{owner}/{repo}/issues/{index}/reactions": {
       "get": {
         "consumes": [
@@ -9010,6 +9181,39 @@
         }
       }
     },
+    "/repos/{owner}/{repo}/new_pin_allowed": {
+      "get": {
+        "produces": [
+          "application/json"
+        ],
+        "tags": [
+          "repository"
+        ],
+        "summary": "Returns if new Issue Pins are allowed",
+        "operationId": "repoNewPinAllowed",
+        "parameters": [
+          {
+            "type": "string",
+            "description": "owner of the repo",
+            "name": "owner",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "string",
+            "description": "name of the repo",
+            "name": "repo",
+            "in": "path",
+            "required": true
+          }
+        ],
+        "responses": {
+          "200": {
+            "$ref": "#/responses/RepoNewIssuePinsAllowed"
+          }
+        }
+      }
+    },
     "/repos/{owner}/{repo}/notifications": {
       "get": {
         "consumes": [
@@ -9302,6 +9506,39 @@
         }
       }
     },
+    "/repos/{owner}/{repo}/pulls/pinned": {
+      "get": {
+        "produces": [
+          "application/json"
+        ],
+        "tags": [
+          "repository"
+        ],
+        "summary": "List a repo's pinned pull requests",
+        "operationId": "repoListPinnedPullRequests",
+        "parameters": [
+          {
+            "type": "string",
+            "description": "owner of the repo",
+            "name": "owner",
+            "in": "path",
+            "required": true
+          },
+          {
+            "type": "string",
+            "description": "name of the repo",
+            "name": "repo",
+            "in": "path",
+            "required": true
+          }
+        ],
+        "responses": {
+          "200": {
+            "$ref": "#/responses/PullRequestList"
+          }
+        }
+      }
+    },
     "/repos/{owner}/{repo}/pulls/{index}": {
       "get": {
         "produces": [
@@ -18664,6 +18901,11 @@
           "format": "int64",
           "x-go-name": "OriginalAuthorID"
         },
+        "pin_order": {
+          "type": "integer",
+          "format": "int64",
+          "x-go-name": "PinOrder"
+        },
         "pull_request": {
           "$ref": "#/definitions/PullRequestMeta"
         },
@@ -19224,6 +19466,21 @@
       },
       "x-go-package": "code.gitea.io/gitea/modules/structs"
     },
+    "NewIssuePinsAllowed": {
+      "description": "NewIssuePinsAllowed represents an API response that says if new Issue Pins are allowed",
+      "type": "object",
+      "properties": {
+        "issues": {
+          "type": "boolean",
+          "x-go-name": "Issues"
+        },
+        "pull_requests": {
+          "type": "boolean",
+          "x-go-name": "PullRequests"
+        }
+      },
+      "x-go-package": "code.gitea.io/gitea/modules/structs"
+    },
     "NodeInfo": {
       "description": "NodeInfo contains standardized way of exposing metadata about a server running one of the distributed social networks",
       "type": "object",
@@ -19934,6 +20191,11 @@
           "type": "string",
           "x-go-name": "PatchURL"
         },
+        "pin_order": {
+          "type": "integer",
+          "format": "int64",
+          "x-go-name": "PinOrder"
+        },
         "requested_reviewers": {
           "type": "array",
           "items": {
@@ -22176,6 +22438,12 @@
         "$ref": "#/definitions/IssueConfigValidation"
       }
     },
+    "RepoNewIssuePinsAllowed": {
+      "description": "RepoNewIssuePinsAllowed",
+      "schema": {
+        "$ref": "#/definitions/NewIssuePinsAllowed"
+      }
+    },
     "Repository": {
       "description": "Repository",
       "schema": {