TF-2677 Create server settings capability & model

server_settings/lib/server_settings/server_settings_id.dart

@@ -0,0 +1,23 @@
+import 'package:equatable/equatable.dart';
+import 'package:jmap_dart_client/jmap/core/id.dart';
+
+enum ServerSettingsIdType {
+  singleton('singleton');
+
+  const ServerSettingsIdType(this.value);
+
+  final String value;
+}
+
+class ServerSettingsId with EquatableMixin {
+  final Id id;
+
+  ServerSettingsId({required this.id});
+
+  @override
+  List<Object?> get props => [id];
+}
+
+extension ServerSettingsIdExtension on ServerSettingsId {
+  static ServerSettingsId get serverSettingsIdSingleton => ServerSettingsId(id: Id(ServerSettingsIdType.singleton.value));
+}