added support for multiple accounts, guardian login bugfixes, ui changes

lib/api/marianumconnect/queries/auth_logout/auth_logout.dart

@@ -1,6 +1,8 @@
 import 'package:dio/dio.dart';
 
 import '../../auth/token_storage.dart';
+import '../../marianumconnect_api.dart';
+import '../../marianumconnect_endpoint.dart';
 import '../../marianumconnect_query.dart';
 
 /// Revokes the stored MC bearer token both server-side and locally. Best-effort
@@ -24,4 +26,17 @@ class AuthLogout extends MarianumConnectQuery {
       await _tokenStorage.clear();
     }
   }
+
+  /// Revokes the token of an inactive account; the stored (active) token is
+  /// left alone. Best-effort.
+  static Future<void> revoke(String token) async {
+    try {
+      await MarianumConnectApi.plainDio().post<void>(
+        MarianumConnectEndpoint.resolve('auth/logout'),
+        options: Options(headers: {'Authorization': 'Bearer $token'}),
+      );
+    } on DioException catch (_) {
+      // ignore
+    }
+  }
 }