add off all to event emitter

Author: anishnag

livekit-rtc/livekit/rtc/event_emitter.py

@@ -198,3 +198,7 @@ def greet(name):
         """
         if event in self._events:
             self._events[event].discard(callback)
+
+    def off_all(self):
+        """Unregister all callbacks from all events."""
+        self._events.clear()