Allow code search by filename (#32210)

This is a large and complex PR, so let me explain in detail its changes.

First, I had to create new index mappings for Bleve and ElasticSerach as
the current ones do not support search by filename. This requires Gitea
to recreate the code search indexes (I do not know if this is a breaking
change, but I feel it deserves a heads-up).

I've used [this
approach](https://www.elastic.co/guide/en/elasticsearch/reference/7.17/analysis-pathhierarchy-tokenizer.html)
to model the filename index. It allows us to efficiently search for both
the full path and the name of a file. Bleve, however, does not support
this out-of-box, so I had to code a brand new [token
filter](https://blevesearch.com/docs/Token-Filters/) to generate the
search terms.

I also did an overhaul in the `indexer_test.go` file. It now asserts the
order of the expected results (this is important since matches based on
the name of a file are more relevant than those based on its content).
I've added new test scenarios that deal with searching by filename. They
use a new repo included in the Gitea fixture.

The screenshot below depicts how Gitea shows the search results. It
shows results based on content in the same way as the current version
does. In matches based on the filename, the first seven lines of the
file contents are shown (BTW, this is how GitHub does it).


![image](https://github.com/user-attachments/assets/9d938d86-1a8d-4f89-8644-1921a473e858)

Resolves #32096

---------

Signed-off-by: Bruno Sofiato <bruno.sofiato@gmail.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/tests/integration/api_org_test.go b/tests/integration/api_org_test.go
index 70d3a446f7..fff121490c 100644
--- a/tests/integration/api_org_test.go
+++ b/tests/integration/api_org_test.go
@@ -177,7 +177,7 @@ func TestAPIGetAll(t *testing.T) {
 	var apiOrgList []*api.Organization
 
 	DecodeJSON(t, resp, &apiOrgList)
-	assert.Len(t, apiOrgList, 12)
+	assert.Len(t, apiOrgList, 13)
 	assert.Equal(t, "Limited Org 36", apiOrgList[1].FullName)
 	assert.Equal(t, "limited", apiOrgList[1].Visibility)
 
@@ -186,7 +186,7 @@ func TestAPIGetAll(t *testing.T) {
 	resp = MakeRequest(t, req, http.StatusOK)
 
 	DecodeJSON(t, resp, &apiOrgList)
-	assert.Len(t, apiOrgList, 8)
+	assert.Len(t, apiOrgList, 9)
 	assert.Equal(t, "org 17", apiOrgList[0].FullName)
 	assert.Equal(t, "public", apiOrgList[0].Visibility)
 }