Add support for joining rooms from a space. (#4501)

* Add support for joining rooms from a space.

Doesn't yet handle the Join button 🤔

* Handle the join button for both rooms and spaces.

Also refactor more instances of spaceRoom to spaceRoomProxy.

ElementX/Sources/UITests/UITestsAppCoordinator.swift

@@ -574,7 +574,8 @@ class MockScreen: Identifiable {
             let clientProxy = ClientProxyMock(.init(userID: "@mock:client.com",
                                                     deviceID: "MOCKCLIENT",
                                                     roomSummaryProvider: RoomSummaryProviderMock(.init(state: .loaded(.mockRooms))),
-                                                    joinedSpaceRooms: .mockSingleRoom))
+                                                    joinedSpaceRooms: .mockSingleRoom,
+                                                    roomPreviews: [SpaceRoomProxyProtocol].mockSpaceList.map(RoomPreviewProxyMock.init)))
             
             // The tab bar remains hidden for the non-spaces tests as we don't supply any mock spaces.
             let spaceServiceProxy = SpaceServiceProxyMock(id == .userSessionSpacesFlow ? .populated : .init())