Impossible to rate medias from Plex Discover

[simonc56]

Describe the Bug

Plex Discover allows to get Movies and Shows that user don't have in PMS library.
Problem : the rate() function do not work for those medias found with discover.provider.plex.tv it raises a plexapi.exceptions.NotFound.

Movies and Shows (found from Plex Discover) rating can be edited with Plex Client, we shoud be able to do it through Plex API too.

Code Snippets

>>> myMovie
<Movie:nan:Asterix-&-Obelix:-Th>
>>> myMovie.rate(10.0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Users\me\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\plexapi\mixins.py", line 318, in rate
    self._server.query(key, method=self._server._session.put)
  File "C:\Users\me\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\site-packages\plexapi\server.py", line 753, in query
    raise NotFound(message)
plexapi.exceptions.NotFound: (404) not_found; https://metadata.provider.plex.tv/:/rate?key=nan&identifier=com.plexapp.plugins.library&rating=10.0 <Error error="Not Found" message="Not Found" statusCode="404"/>

Expected Behavior

No error raised.
Just like items from user's PMS library.

Additional Context

Requests to rate items from Plex Discover are :

Rate :
https://discover.provider.plex.tv/actions/rate?identifier=tv.plex.provider.discover&key=5e16138e04b9ad001e9a74ca&rating=4

Remove rating :
https://discover.provider.plex.tv/actions/rate?identifier=tv.plex.provider.discover&key=5e16138e04b9ad001e9a74ca&rating=-1

Similar to issue #1067

Operating System and Version

Windows 10

Plex Media Server Version

1.29.2.6364

Python Version

3.9

PlexAPI Version

4.13.1