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

sytest-whitelist

@@ -181,7 +181,11 @@ Outbound federation can query profile data
 /event/ on joined room works
 /event/ does not allow access to events before the user joined
 Federation key API allows unsigned requests for keys
+GET /publicRooms lists rooms
+GET /publicRooms includes avatar URLs
 Can paginate public room list
+GET /publicRooms lists newly-created room
+Name/topic keys are correct
 GET /directory/room/:room_alias yields room ID
 PUT /directory/room/:room_alias creates alias
 Room aliases can contain Unicode