Selecting a server that doesn't support login now fails instead of letting you continue to a failure later. (#3342)

* Fail configuration of the authentication service if the homeserver doesn't support login.

* Move the ServerSelectionCoordinator logic into the ViewModel.

- Handle the new login alert.
- Add more tests

ElementX/Sources/Screens/Authentication/ServerConfirmationScreen/ServerConfirmationScreenModels.swift

@@ -72,6 +72,8 @@ enum ServerConfirmationScreenAlert: Hashable {
     case invalidWellKnown(String)
     /// An alert that allows the user to learn about sliding sync.
     case slidingSync
+    /// An alert that informs the user that login isn't supported.
+    case login
     /// An alert that informs the user that registration isn't supported.
     case registration
     /// An unknown error has occurred.

ElementX/Sources/Screens/Authentication/ServerConfirmationScreen/ServerConfirmationScreenViewModel.swift

@@ -82,6 +82,8 @@ class ServerConfirmationScreenViewModel: ServerConfirmationScreenViewModelType,
                 displayError(.invalidWellKnown(error))
             case .slidingSyncNotAvailable:
                 displayError(.slidingSync)
+            case .loginNotSupported:
+                displayError(.login)
             case .registrationNotSupported:
                 displayError(.registration)
             default:
@@ -117,9 +119,13 @@ class ServerConfirmationScreenViewModel: ServerConfirmationScreenViewModelType,
                                                  message: L10n.screenChangeServerErrorNoSlidingSyncMessage,
                                                  primaryButton: .init(title: L10n.actionLearnMore, role: .cancel, action: openURL),
                                                  secondaryButton: .init(title: L10n.actionCancel, action: nil))
+        case .login:
+            state.bindings.alertInfo = AlertInfo(id: .login,
+                                                 title: L10n.commonServerNotSupported,
+                                                 message: L10n.screenLoginErrorUnsupportedAuthentication)
         case .registration:
             state.bindings.alertInfo = AlertInfo(id: .registration,
-                                                 title: L10n.errorUnknown,
+                                                 title: L10n.commonServerNotSupported,
                                                  message: L10n.errorAccountCreationNotPossible)
         case .unknownError:
             state.bindings.alertInfo = AlertInfo(id: .unknownError)