diff: Reuse request validation logic for DiffStats
Request DiffStatsRequest
implements requestWithLeftRightCommitIds
perfectly, so we should reuse the same validation logic like CommitDiff,
CommitDelta, RawDiff and RawPatch.
Request DiffStatsRequest
implements requestWithLeftRightCommitIds
perfectly, so we should reuse the same validation logic like CommitDiff,
CommitDelta, RawDiff and RawPatch.