Simplify how git repositories are opened (#28937)

## Purpose
This is a refactor toward building an abstraction over managing git
repositories.
Afterwards, it does not matter anymore if they are stored on the local
disk or somewhere remote.

## What this PR changes
We used `git.OpenRepository` everywhere previously.
Now, we should split them into two distinct functions:

Firstly, there are temporary repositories which do not change:

```go
git.OpenRepository(ctx, diskPath)
```

Gitea managed repositories having a record in the database in the
`repository` table are moved into the new package `gitrepo`:

```go
gitrepo.OpenRepository(ctx, repo_model.Repo)
```

Why is `repo_model.Repository` the second parameter instead of file
path?
Because then we can easily adapt our repository storage strategy.
The repositories can be stored locally, however, they could just as well
be stored on a remote server.

## Further changes in other PRs
- A Git Command wrapper on package `gitrepo` could be created. i.e.
`NewCommand(ctx, repo_model.Repository, commands...)`. `git.RunOpts{Dir:
repo.RepoPath()}`, the directory should be empty before invoking this
method and it can be filled in the function only. #28940
- Remove the `RepoPath()`/`WikiPath()` functions to reduce the
possibility of mistakes.

---------

Co-authored-by: delvh <dev.lh@web.de>

3 files changed, 7 insertions, 4 deletions

diff --git a/modules/repository/branch.go b/modules/repository/branch.go
index cd45f16227..e448490f4a 100644
--- a/modules/repository/branch.go
+++ b/modules/repository/branch.go
@@ -11,6 +11,7 @@ import (
 	repo_model "code.gitea.io/gitea/models/repo"
 	"code.gitea.io/gitea/modules/container"
 	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/gitrepo"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/timeutil"
 )
@@ -24,9 +25,9 @@ func SyncRepoBranches(ctx context.Context, repoID, doerID int64) (int64, error)
 
 	log.Debug("SyncRepoBranches: in Repo[%d:%s]", repo.ID, repo.FullName())
 
-	gitRepo, err := git.OpenRepository(ctx, repo.RepoPath())
+	gitRepo, err := gitrepo.OpenRepository(ctx, repo)
 	if err != nil {
-		log.Error("OpenRepository[%s]: %w", repo.RepoPath(), err)
+		log.Error("OpenRepository[%s]: %w", repo.FullName(), err)
 		return 0, err
 	}
 	defer gitRepo.Close()
diff --git a/modules/repository/generate.go b/modules/repository/generate.go
index f8478b8c18..b32c4e058e 100644
--- a/modules/repository/generate.go
+++ b/modules/repository/generate.go
@@ -19,6 +19,7 @@ import (
 	repo_model "code.gitea.io/gitea/models/repo"
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/gitrepo"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/util"
 
@@ -271,7 +272,7 @@ func generateGitContent(ctx context.Context, repo, templateRepo, generateRepo *r
 		repo.DefaultBranch = templateRepo.DefaultBranch
 	}
 
-	gitRepo, err := git.OpenRepository(ctx, repo.RepoPath())
+	gitRepo, err := gitrepo.OpenRepository(ctx, repo)
 	if err != nil {
 		return fmt.Errorf("openRepository: %w", err)
 	}
diff --git a/modules/repository/repo.go b/modules/repository/repo.go
index 5352da0378..fc3af04071 100644
--- a/modules/repository/repo.go
+++ b/modules/repository/repo.go
@@ -19,6 +19,7 @@ import (
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/container"
 	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/gitrepo"
 	"code.gitea.io/gitea/modules/lfs"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/migration"
@@ -291,7 +292,7 @@ func SyncRepoTags(ctx context.Context, repoID int64) error {
 		return err
 	}
 
-	gitRepo, err := git.OpenRepository(ctx, repo.RepoPath())
+	gitRepo, err := gitrepo.OpenRepository(ctx, repo)
 	if err != nil {
 		return err
 	}