Require type hints in the handlers module. (#10831)

Adds missing type hints to methods in the synapse.handlers
module and requires all methods to have type hints there.

This also removes the unused construct_auth_difference method
from the FederationHandler.

synapse/handlers/room_list.py

@@ -14,7 +14,7 @@
 
 import logging
 from collections import namedtuple
-from typing import TYPE_CHECKING, Optional, Tuple
+from typing import TYPE_CHECKING, Any, Optional, Tuple
 
 import msgpack
 from unpaddedbase64 import decode_base64, encode_base64
@@ -33,7 +33,7 @@ from synapse.api.errors import (
     SynapseError,
 )
 from synapse.types import JsonDict, ThirdPartyInstanceID
-from synapse.util.caches.descriptors import cached
+from synapse.util.caches.descriptors import _CacheContext, cached
 from synapse.util.caches.response_cache import ResponseCache
 
 from ._base import BaseHandler
@@ -169,7 +169,7 @@ class RoomListHandler(BaseHandler):
             ignore_non_federatable=from_federation,
         )
 
-        def build_room_entry(room):
+        def build_room_entry(room: JsonDict) -> JsonDict:
             entry = {
                 "room_id": room["room_id"],
                 "name": room["name"],
@@ -249,10 +249,10 @@ class RoomListHandler(BaseHandler):
         self,
         room_id: str,
         num_joined_users: int,
-        cache_context,
+        cache_context: _CacheContext,
         with_alias: bool = True,
         allow_private: bool = False,
-    ) -> Optional[dict]:
+    ) -> Optional[JsonDict]:
         """Returns the entry for a room
 
         Args:
@@ -507,7 +507,7 @@ class RoomListNextBatch(
             )
         )
 
-    def copy_and_replace(self, **kwds) -> "RoomListNextBatch":
+    def copy_and_replace(self, **kwds: Any) -> "RoomListNextBatch":
         return self._replace(**kwds)