DEV: Log Reviewable actions (#36076)

With reviewables now being able to have multiple actions performed on
them, we don't want to update the final reviewable state until an action
from every action bundle has been performed.

This change makes use of the new `ReviewableActionLog`, logging actions
when they occur, then checking to see if a reviewable has had all
actions performed before finalising it.

db/migrate/20251118002306_add_bundle_to_reviewable_action_logs.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+class AddBundleToReviewableActionLogs < ActiveRecord::Migration[8.0]
+  def change
+    add_column :reviewable_action_logs, :bundle, :string, default: "legacy-actions", null: false
+    add_index :reviewable_action_logs, :bundle
+  end
+end