* Add a picker mode to the ServerConfirmationScreen.
* Hook up the account provider picker in authentication the flow.
Simplify the authentication flow coordinator, removing the restricted state.
* UI/Snapshot tests.
* Don't query the homeserver until confirming it (or selecting a different one).
* Setup the infrastructure to test AuthenticationService.
Implement basic tests for configuration & password login.
* Use the real AuthenticationService with a mock Client in all of the tests.
* Add tests for the ServerConfirmationScreenViewModel.
* Remove redundant view state and test for it.
