SYN-12: Implement auth for deletion by adding a 'delete_level' on the ops levels event

SYN-12 # comment Auth has been added.

synapse/storage/schema/delta/v4.sql

@@ -5,3 +5,7 @@ CREATE TABLE IF NOT EXISTS deletions (
 
 CREATE INDEX IF NOT EXISTS deletions_event_id ON deletions (event_id);
 CREATE INDEX IF NOT EXISTS deletions_deletes ON deletions (deletes);
+
+ALTER TABLE room_ops_levels ADD COLUMN delete_level INTEGER;
+
+PRAGMA user_version = 4;