Populating the path property of the ydoc

[brichet]

Description

The path property of the ydoc is not populated.

This is probably a regression included in #174.
The path used to be set here:

jupyter-collaboration/jupyter_server_ydoc/ydoc.py

Line 127 in 5476673

self.room.document.path = file_path

Reproduce

Open a document in collaborative mode and try to get the path from the ydoc.

Expected behavior

The path to be populated.

Suggestion

Set the path should be trivial at initialization, i.e. at

jupyter-collaboration/projects/jupyter-server-ydoc/jupyter_server_ydoc/rooms.py

Line 44 in b8fafc0

self._document = YDOCS.get(self._file_type, YFILE)(self.ydoc)

Then we should probably update the path if it has changed, probably from

jupyter-collaboration/projects/jupyter-server-ydoc/jupyter_server_ydoc/loaders.py

Line 183 in b8fafc0

async def _watch_file(self) -> None: