Add block on pending codeowner reviews branch protection

[Naxdy]

This commit introduces a new branch protection rule that allows merge blocking if there are pending reviews from one or more code owners (as defined in any valid CODEOWNERS file). This is determined by evaluating each rule present in the CODEOWNERS file individually. For every rule, at least one named code owner (or member of a code owner team) must have given an approving review for merging to be possible.

Closes #32602

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This PR does NOT display code owners separately from other reviewers (#28137), as I think it makes sense to do that in a separate PR, as it doesn't require any database migrations.

Screenshot

Pull Request

Branch Protection Rule

Unresolved questions

• Does this warrant a doc change? Relevant PR: https://gitea.com/gitea/docs/pulls/245

[lunny]

The logic appears overly complex and doesn’t seem correct. I ran a test, and it didn’t work as expected. Could you please rewrite it to make it clearer and more readable?

[Naxdy]

I ran a test, and it didn’t work as expected.

Can you give me more info about that, like the codeowner file you used and what you expected vs. what happened?

[Naxdy]

Also went and amended it to be a bit more concise. The behavior should be unchanged though, so I'd still be interested in your findings.

[Naxdy]

Relevant PR for gitea docs, for if/when this is merged: https://gitea.com/gitea/docs/pulls/245

[lunny]

This may conflict with the UI for protected branches in forked repositories.

[Naxdy]

I went with the same logic as here:

https://github.com/go-gitea/gitea/tree/ce73de0e890fa24becc38c83b466432d7d70ea85/services/issue/pull.go#L177-L190

Which ensures code owners don't get review requests in forked repositories. I think it makes sense to do something similar here? That is, don't require reviews from code owners who potentially have nothing to do with your forked repo.