gitserver: Add CommitLog API to replace client-side Commits

[eseliger]

This PR moves the Commits API to the server side and is the last gRPC API to migrate (considering LogReverseEach is already out for review).

Yet again (lack of integration tests), I had to reimplement some logic for the rockskip tests. We should investigate ways to run tests against actual gitservers, ideally without having to compile the whole server image and running that.

Closes https://github.com/sourcegraph/sourcegraph/issues/61690

Test plan:

Existing tests are still passing, moved the ~extensive unit test coverage this had on the client side to the server side, and reimplemented the subrepoperms tests for the new backend.

[eseliger]

• gitserver: Deprecate Exec and remove localGit #62773 : 3 dependent PRs (#62774 , #62801 , #62825 )
• gitserver: Remove and deprecate no_timeout option from exec #62743
• rockskip: Replace second long-running process with gRPC API #62734
• gitserver: Add CommitLog API to replace client-side Commits #62606 👈
• gitserver: Fix duration reported for ChangedFiles #62603
• gitserver: Make ReadDir return an iterator on client side #62602
• gitserver: Move implementation of HasCommitAfter to caller #62520
• gitserver: Always use Commits in HasCommitAfter #62519
• gitserver: Implement CommitLog using Commits #62518
• gitserver: Move CommitsUniqueToBranch to callsite #62514
• gitserver: Implement CommitsUniqueToBranch using Commits #62513
• gitserver: Implement Stat and ReadDir in gRPC API #62107
• main

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[eseliger]

These didn't exist previously, I added tests for a few more settings here than we had before, but these are a bit more involved and don't impact the goal of finalizing the migration - so I decided to leave that for a rainy day.

[eseliger]

Thoughts on this? It's basically a batched GetCommit, and that response already carries the optional modified_files slice that we need for subrepo perms checks.

Alternatives I considered:

• Making a separate type, but otherwise same contents
• Add ModifiedFiles to message GitCommit directly, and use field masks to not compute it (sadly they're purely additive so I'd need to always send a mask for the default case of don't include them)
• Use a view field like Google has in their gRPC APIs (I dislike that kinda, because there's no good tooling to know which view of a resource you got back -> easy to use a field on the client side that wasn't actually sent

[ggilmore]

nit: can we extract that into a constant?

Suggested change

	if data[0] != '\x1e' {
	const recordSeparator = '\x1e'
	if data[0] != recordSeparator {

[eseliger]

Merge activity

• May 21, 9:22 AM EDT: @eseliger merged this pull request with Graphite.