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

federationapi/routing/routing.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/gorilla/mux"
 	"github.com/matrix-org/dendrite/clientapi/jsonerror"
+	currentstateAPI "github.com/matrix-org/dendrite/currentstateserver/api"
 	eduserverAPI "github.com/matrix-org/dendrite/eduserver/api"
 	federationSenderAPI "github.com/matrix-org/dendrite/federationsender/api"
 	"github.com/matrix-org/dendrite/internal/config"
@@ -52,6 +53,7 @@ func Setup(
 	keys gomatrixserverlib.JSONVerifier,
 	federation *gomatrixserverlib.FederationClient,
 	userAPI userapi.UserInternalAPI,
+	stateAPI currentstateAPI.CurrentStateInternalAPI,
 ) {
 	v2keysmux := publicAPIMux.PathPrefix(pathPrefixV2Keys).Subrouter()
 	v1fedmux := publicAPIMux.PathPrefix(pathPrefixV1Federation).Subrouter()
@@ -291,4 +293,10 @@ func Setup(
 			return Backfill(httpReq, request, rsAPI, vars["roomID"], cfg)
 		},
 	)).Methods(http.MethodGet)
+
+	v1fedmux.Handle("/publicRooms",
+		httputil.MakeExternalAPI("federation_public_rooms", func(req *http.Request) util.JSONResponse {
+			return GetPostPublicRooms(req, rsAPI, stateAPI)
+		}),
+	).Methods(http.MethodGet)
 }