Implement GET /_matrix/client/r0/rooms/{roomId}/state/{eventType}/{stateKey}
See r0.6.0 spec : https://matrix.org/docs/spec/client_server/r0.6.0#id256
Steps:
- use
RoomApi.getEvents
,RoomApi.getEventsContents
andRoomApi.getEventsContents
to get contents and sender - add a new API endpoint route and implement API call based on URL parameters