room filtering doesn't show rooms who are named based on their alias?

I'm in a room with an alias of `#_xmpp_muc.xmpp.org_xsf:matrix.org`.

But trying to filter for `xsf` in the RoomList silently fails; it looks like we're only searching m.room.name or something rather than the alias?  In practice we should surely be searching based on whatever label is shown on the RoomTile in the RoomList.