add plugin camera desktop

plugins/camera_desktop/example/test/widget_test.dart

@@ -0,0 +1,9 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:camera_desktop_example/main.dart';
+
+void main() {
+  testWidgets('CameraExampleApp builds', (WidgetTester tester) async {
+    await tester.pumpWidget(const CameraExampleApp());
+    expect(find.text('Camera Desktop Example'), findsOneWidget);
+  });
+}