* Add `InvitedRoom` to wrap Rust SDK Rooms in 'invited' membership state.
At the moment, this is a wrapper that allows us to call `Room.leave()` without having to initialise the room's timeline (which is impossible).
* Add `MatrixRoom.getInvitedRoom(roomId)` to get one of these rooms.
Also, `RustRoomFactory` now has a `createInvitedRoom` method for this.
* Adapt `AcceptDeclineInvitePresenter` to use the new APIs.