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

roomserver/storage/interface.go

@@ -139,4 +139,8 @@ type Database interface {
 	EventsFromIDs(ctx context.Context, eventIDs []string) ([]types.Event, error)
 	// Look up the room version for a given room.
 	GetRoomVersionForRoom(ctx context.Context, roomID string) (gomatrixserverlib.RoomVersion, error)
+	// Publish or unpublish a room from the room directory.
+	PublishRoom(ctx context.Context, roomID string, publish bool) error
+	// Returns a list of room IDs for rooms which are published.
+	GetPublishedRooms(ctx context.Context) ([]string, error)
 }