Add patch-id column to merge_request_diffs table

What does this MR do and why?

Add patch-id column to merge_request_diffs

Database

Up

main: == [advisory_lock_connection] object_id: 222940, pg_backend_pid: 77335
main: == 20230718234602 AddPatchIdToMergeRequestDiffs: migrating ====================
main: -- add_column(:merge_request_diffs, :patch_id_sha, :binary)
main:    -> 0.0014s
main: == 20230718234602 AddPatchIdToMergeRequestDiffs: migrated (0.0051s) ===========

Down

main: == [advisory_lock_connection] object_id: 223660, pg_backend_pid: 90728
main: == 20230718234602 AddPatchIdToMergeRequestDiffs: reverting ====================
main: -- remove_column(:merge_request_diffs, :patch_id, :text, {:limit=>50})
main:    -> 0.0016s
main: == 20230718234602 AddPatchIdToMergeRequestDiffs: reverted (0.0066s) ===========

Related to #384327 (closed)