Migrate desktop_photo_search to top level (#1002)

desktop_photo_search/fluent_ui/lib/src/model/search.dart

@@ -0,0 +1,36 @@
+// Copyright 2019 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:convert';
+
+import 'package:built_collection/built_collection.dart';
+import 'package:built_value/built_value.dart';
+import 'package:built_value/serializer.dart';
+
+import '../serializers.dart';
+import '../unsplash/photo.dart';
+
+part 'search.g.dart';
+
+abstract class Search implements Built<Search, SearchBuilder> {
+  factory Search([void Function(SearchBuilder)? updates]) = _$Search;
+  Search._();
+
+  @BuiltValueField(wireName: 'query')
+  String get query;
+
+  @BuiltValueField(wireName: 'results')
+  BuiltList<Photo> get results;
+
+  String toJson() {
+    return json.encode(serializers.serializeWith(Search.serializer, this));
+  }
+
+  static Search? fromJson(String jsonString) {
+    return serializers.deserializeWith(
+        Search.serializer, json.decode(jsonString));
+  }
+
+  static Serializer<Search> get serializer => _$searchSerializer;
+}