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/send_test.go

@@ -111,6 +111,13 @@ func (t *testRoomserverAPI) PerformJoin(
 ) {
 }
 
+func (t *testRoomserverAPI) PerformPublish(
+	ctx context.Context,
+	req *api.PerformPublishRequest,
+	res *api.PerformPublishResponse,
+) {
+}
+
 func (t *testRoomserverAPI) PerformLeave(
 	ctx context.Context,
 	req *api.PerformLeaveRequest,
@@ -168,6 +175,14 @@ func (t *testRoomserverAPI) QueryMembershipForUser(
 	return fmt.Errorf("not implemented")
 }
 
+func (t *testRoomserverAPI) QueryPublishedRooms(
+	ctx context.Context,
+	request *api.QueryPublishedRoomsRequest,
+	response *api.QueryPublishedRoomsResponse,
+) error {
+	return fmt.Errorf("not implemented")
+}
+
 // Query a list of membership events for a room
 func (t *testRoomserverAPI) QueryMembershipsForRoom(
 	ctx context.Context,