Check if a room looks like a DM rooms on joining

and mark it as one if so.

Also change the heuristic to only count rooms with 2 total members rather than 2 joined members, otherwise this is going to mark any room as a DM if someone creates a room, invites a bunch of people and you happen to be first to join.

src/Rooms.js

@@ -68,7 +68,7 @@ export function looksLikeDirectMessageRoom(room, me) {
         // Used to split rooms via tags
         const tagNames = Object.keys(room.tags);
         // Used for 1:1 direct chats
-        const joinedMembers = room.getJoinedMembers();
+        const joinedMembers = room.currentState.getMembers();
 
         // Show 1:1 chats in seperate "Direct Messages" section as long as they haven't
         // been moved to a different tag section