Update web implementation to use platform interface.

just_audio/example/lib/generated_plugin_registrant.dart

@@ -6,7 +6,7 @@
 import 'dart:ui';
 
 import 'package:audio_session/audio_session_web.dart';
-import 'package:just_audio/just_audio_web.dart';
+import 'package:just_audio_web/just_audio_web.dart';
 
 import 'package:flutter_web_plugins/flutter_web_plugins.dart';
 

just_audio/example/pubspec.lock

@@ -121,6 +121,13 @@ packages:
       relative: true
     source: path
     version: "0.0.1"
+  just_audio_web:
+    dependency: "direct dev"
+    description:
+      path: "../../just_audio_web"
+      relative: true
+    source: path
+    version: "0.0.1"
   matcher:
     dependency: transitive
     description:

just_audio/example/pubspec.yaml

@@ -18,6 +18,8 @@ dev_dependencies:
 
   just_audio:
     path: ../
+  just_audio_web:
+    path: ../../just_audio_web
 
 # For information on the generic Dart part of this file, see the
 # following page: https://dart.dev/tools/pub/pubspec