Add module API method to resolve a room alias to a room ID (#13428)

Co-authored-by: MattC <buffless-matt@users.noreply.github.com>
Co-authored-by: Brendan Abolivier <babolivier@matrix.org>

synapse/module_api/__init__.py

@@ -1452,6 +1452,30 @@ class ModuleApi:
             start_timestamp, end_timestamp
         )
 
+    async def lookup_room_alias(self, room_alias: str) -> Tuple[str, List[str]]:
+        """
+        Get the room ID associated with a room alias.
+
+        Added in Synapse v1.65.0.
+
+        Args:
+            room_alias: The alias to look up.
+
+        Returns:
+            A tuple of:
+                The room ID (str).
+                Hosts likely to be participating in the room ([str]).
+
+        Raises:
+            SynapseError if room alias is invalid or could not be found.
+        """
+        alias = RoomAlias.from_string(room_alias)
+        (room_id, hosts) = await self._hs.get_room_member_handler().lookup_room_alias(
+            alias
+        )
+
+        return room_id.to_string(), hosts
+
 
 class PublicRoomListManager:
     """Contains methods for adding to, removing from and querying whether a room