Allow YRoom to be restarted and allow multi-room kernels (#117)

* remove rooms when they start stopping, not after

* automatically stop empty rooms in background task every 5s

* bump to 10 second interval

* only delete notebook rooms once kernel idle/dead

* fix #111, implement update_session()

* update kernel client to always use latest rooms from YRoomManager

* fix room cleanup for non-notebooks

* ensure returned rooms are kept alive for 10 seconds

* update docstrings

* refactor FileAPI, allow it to be restarted

* allow rooms to be restarted, unify stop() methods

* implement contents lock to prevent overlapping reads/writes

* update YRoomManager to use new stop() API

* stop inactive rooms instead of deleting

* fix extension stopping

* restart inactive rooms instead of deleting

* revert changes to kernel client

* fix empty notebooks after room restart

* add observe_jupyter_ydoc() method for consumers

* fix typos and missing type annotations (thanks @JGuinegagne)

* disable _watch_rooms() task

Author: dlqqq

jupyter_server_documents/app.py

@@ -101,5 +101,5 @@ def _link_jupyter_server_extension(self, server_app):
     async def stop_extension(self):
         self.log.info("Stopping `jupyter_server_documents` server extension.")
         if self.yroom_manager:
-            await self.yroom_manager.stop()
+            self.yroom_manager.stop()
         self.log.info("`jupyter_server_documents` server extension is shut down. Goodbye!")