Force DMs to always be red notifications

This also passes the tagId to the sublist so it doesn't have to rip it out of the `layout`. It doesn't get a layout until later anyways, which causes some null issues.

src/components/views/rooms/RoomList2.tsx

@@ -193,6 +193,7 @@ export default class RoomList2 extends React.Component<IProps, IState> {
             components.push(
                 <RoomSublist2
                     key={`sublist-${orderedTagId}`}
+                    tagId={orderedTagId}
                     forRooms={true}
                     rooms={orderedRooms}
                     startAsHidden={aesthetics.defaultHidden}