Replace publicroomsapi with a combination of clientapi/roomserver/currentstateserver (#1174)

* Use content_value instead of membership

* Fix build

* Replace publicroomsapi with a combination of clientapi/roomserver/currentstateserver

- All public rooms paths are now handled by clientapi
- Requests to (un)publish rooms are sent to the roomserver via `PerformPublish`
  which are stored in a new `published_table.go`
- Requests for public rooms are handled in clientapi by:
    * Fetch all room IDs which are published using `QueryPublishedRooms` on the roomserver.
    * Apply pagination parameters to the slice.
    * Do a `QueryBulkStateContent` request to the currentstateserver to pull out
      required state event *content* (not entire events).
    * Aggregate and return the chunk.

Mostly but not fully implemented (DB queries on currentstateserver are missing)

* Fix pq query

* Make postgres work

* Make sqlite work

* Fix tests

* Unbreak pagination tests

* Linting

cmd/dendrite-federation-api-server/main.go

@@ -33,7 +33,7 @@ func main() {
 
 	federationapi.AddPublicRoutes(
 		base.PublicAPIMux, base.Cfg, userAPI, federation, keyRing,
-		rsAPI, fsAPI, base.EDUServerClient(),
+		rsAPI, fsAPI, base.EDUServerClient(), base.CurrentStateAPIClient(),
 	)
 
 	base.SetupAndServeHTTP(string(base.Cfg.Bind.FederationAPI), string(base.Cfg.Listen.FederationAPI))