feat: introduce ArtplayerToolIframe for iframe control

- Removed the old ArtplayerPluginIframe implementation.
- Added ArtplayerToolIframe class with methods for iframe communication.
- Implemented postMessage and onMessage methods for message handling.
- Created a new TypeScript definition file for ArtplayerToolIframe.
- Updated documentation links to point to the new iframe tool.
- Added npm ignore file and README for the new package.
- Included compiled and uncompiled versions of the new iframe tool.
- Updated package.json with relevant metadata and exports.

docs/iframe.html

@@ -5,7 +5,7 @@
     <meta charset="UTF-8">
     <meta http-equiv="X-UA-Compatible" content="IE=edge">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
-    <title>artplayer-plugin-iframe.js</title>
+    <title>artplayer-tool-iframe.js</title>
     <style>
         html,
         body {
@@ -20,8 +20,8 @@
 <body>
     <div class="artplayer-app" style="width: 100%; height: 100%;"></div>
     <script src="./uncompiled/artplayer/index.js"></script>
-    <script src="./uncompiled/artplayer-plugin-iframe/index.js"></script>
-    <script>ArtplayerPluginIframe.inject();</script>
+    <script src="./uncompiled/artplayer-tool-iframe/index.js"></script>
+    <script>ArtplayerToolIframe.inject();</script>
 </body>
 
 </html>