Addtional type hints for the REST servlets. (#10665)

changelog.d/10665.misc

synapse/rest/client/account_validity.py

synapse/rest/client/capabilities.py

synapse/rest/client/directory.py

synapse/rest/client/pusher.py

synapse/rest/client/read_marker.py

synapse/rest/client/room_upgrade_rest_servlet.py

synapse/rest/client/shared_rooms.py

synapse/rest/client/tags.py

synapse/rest/client/thirdparty.py

synapse/rest/client/tokenrefresh.py

synapse/rest/client/user_directory.py

synapse/rest/client/versions.py

synapse/rest/client/voip.py