Add support multiple projects again

[tyroneyeh]

Closes #12974 and #27984

[tyroneyeh]

Hi @wolfogre

Could you help me take a look at how unit test modules/indexer/issues/internal/tests/tests.go handles this part?

[wolfogre]

Could you help me take a look at how unit test modules/indexer/issues/internal/tests/tests.go handles this part?

8dcdbf6

Main changes:

• Rename ProjectID to ProjectIDs in data model and query conditions.
• So len(ProjectIDs) == 0 (it was ProjectID == 0) means no project, so we need additional NoProject field to query.
• Index definitions of bleve / MeiliSearch / Elasticsearch need to be updated, so do the index versions.
• Update the tests for the changes.

Know issues:

• Not sure if it works with the DB issue indexer; I haven't checked it since it's totally a different logic path.
• Some tests may still fail, but I think they should be easy to understand and fix.

PLEASE NOTE:

• I helped commit this change just to demonstrate how to update the indexer to support multiple projects.
• It doesn't mean I agree or disagree with any of the following:
  • this PR.
  • the idea of multiple projects.
  • replacing Support multiple projects #27984.
• I haven't thought about the feature deeply, so other maintainers may help to review. See also Add unique index for project_issue to prevent duplicate data #30190.

[lunny]

This is not conflicted with #30190. That PR just ensures an issue will only be added once to a project. It will not prevent an issue added to multiple different projects.

[tyroneyeh]

New branch name PR change to #30381