MSC2946: Spaces Summary (round 2) (#2232)

* Initial cut at fixing up MSC2946 to work with latest spec

* bugfix: send response back correctly

* Initial working version of MSC2946

* msc2946: handle suggested_only; remove custom database

As the MSC doesn't require reverse lookups, we can just pull
the room state and inspect via the roomserver database. To
handle this, expand QueryCurrentState to support wildcards.

Use all this and handle `?suggested_only`.

* Sort child rooms

* msc2946: Make TestClientSpacesSummary pass

* msc2946: allow invited rooms to be spidered

* msc2946: support basic federation requests

* fix up go mod

roomserver/api/query.go

@@ -313,7 +313,10 @@ type QueryBulkStateContentResponse struct {
 }
 
 type QueryCurrentStateRequest struct {
-	RoomID      string
+	RoomID         string
+	AllowWildcards bool
+	// State key tuples. If a state_key has '*' and AllowWidlcards is true, returns all matching
+	// state events with that event type.
 	StateTuples []gomatrixserverlib.StateKeyTuple
 }