adding in initial plugin code

lib/multimedia_method_channel.dart

@@ -0,0 +1,17 @@
+import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart';
+
+import 'multimedia_platform_interface.dart';
+
+/// An implementation of [MultimediaPlatform] that uses method channels.
+class MethodChannelMultimedia extends MultimediaPlatform {
+  /// The method channel used to interact with the native platform.
+  @visibleForTesting
+  final methodChannel = const MethodChannel('multimedia');
+
+  @override
+  Future<String?> getPlatformVersion() async {
+    final version = await methodChannel.invokeMethod<String>('getPlatformVersion');
+    return version;
+  }
+}