Space flow improvements. (#4430)

* Space flow improvements

- Use a state machine to select a space.
- Add a SpaceFlowCoordinator for recursively presenting subspaces.
- Get the spaceRoomListProxy when tapping on the space so we can indicate failures.
- Fix the total room count in SpaceListScreen.

* Refactor spaceRoom → spaceRoomProxy.

* Add a UI test for the Spaces flow.

ElementX/Sources/Mocks/ClientProxyMock.swift

@@ -85,6 +85,8 @@ extension ClientProxyMock {
         secureBackupController = SecureBackupControllerMock(.init(recoveryState: configuration.recoveryState))
         resetIdentityReturnValue = .success(IdentityResetHandleSDKMock(.init()))
         
+        spaceService = SpaceServiceProxyMock(.init())
+        
         roomForIdentifierClosure = { [weak self] identifier in
             guard let room = self?.roomSummaryProvider.roomListPublisher.value.first(where: { $0.id == identifier }) else {
                 return nil