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

lib/api/marianumconnect/queries/get_capabilities/guardian_child.g.dart

@@ -12,6 +12,7 @@ _GuardianChild _$GuardianChildFromJson(Map<String, dynamic> json) =>
       firstName: json['firstName'] as String,
       lastName: json['lastName'] as String,
       className: json['className'] as String? ?? '',
+      username: json['username'] as String?,
     );
 
 Map<String, dynamic> _$GuardianChildToJson(_GuardianChild instance) =>
@@ -20,4 +21,5 @@ Map<String, dynamic> _$GuardianChildToJson(_GuardianChild instance) =>
       'firstName': instance.firstName,
       'lastName': instance.lastName,
       'className': instance.className,
+      'username': instance.username,
     };