add viewer/windows files

lib/polyvox_filament.dart

@@ -0,0 +1,17 @@
+// You have generated a new plugin project without
+// specifying the `--platforms` flag. A plugin project supports no platforms is generated.
+// To add platforms, run `flutter create -t plugin --platforms <platforms> .` under the same
+// directory. You can also find a detailed instruction on how to add platforms in the `pubspec.yaml` at https://flutter.dev/docs/development/packages-and-plugins/developing-packages#plugin-platforms.
+
+import 'dart:async';
+
+import 'package:flutter/services.dart';
+
+class PolyvoxFilament {
+  static const MethodChannel _channel = MethodChannel('polyvox_filament');
+
+  static Future<String?> get platformVersion async {
+    final String? version = await _channel.invokeMethod('getPlatformVersion');
+    return version;
+  }
+}