Create android & web plugins (#15)

* create android & web plugins

* apply `flutter format .`

lib/livekit_client_web.dart

@@ -0,0 +1,34 @@
+import 'dart:async';
+// In order to *not* need this ignore, consider extracting the "web" version
+// of your plugin as a separate package, instead of inlining it in the same
+// package as the core of your plugin.
+// ignore: avoid_web_libraries_in_flutter
+// import 'dart:html' as html show window;
+
+import 'package:flutter/services.dart';
+import 'package:flutter_web_plugins/flutter_web_plugins.dart';
+
+/// A web implementation of the Livekit plugin.
+class LiveKitWebPlugin {
+  static void registerWith(Registrar registrar) {
+    final MethodChannel channel = MethodChannel(
+      'livekit_client',
+      const StandardMethodCodec(),
+      registrar,
+    );
+
+    final pluginInstance = LiveKitWebPlugin();
+    channel.setMethodCallHandler(pluginInstance.handleMethodCall);
+  }
+
+  /// Handles method calls over the MethodChannel of this plugin.
+  /// Note: Check the "federated" architecture for a new way of doing this:
+  /// https://flutter.dev/go/federated-plugins
+  Future<dynamic> handleMethodCall(MethodCall call) async {
+    // no-op for now
+    throw PlatformException(
+      code: 'Unimplemented',
+      details: 'livekit for web doesn\'t implement \'${call.method}\'',
+    );
+  }
+}