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.

CHANGELOG.md

@@ -265,7 +265,7 @@ const option = {
 
 - Add `art.type` property to get/set video type
 - Add `art.video` property to get video element
-- Add `artplayer-plugin-iframe` plugin to control player inside iframe
+- Add `artplayer-tool-iframe` plugin to control player inside iframe
 - Add `artplayer-plugin-hls-quality` plugin for adding Hls quality list
 - Add `Artplayer.PLAYBACK_RATE` for default playback rates `[0.5, 0.75, 1, 1.25, 1.5, 2]`
 - Add `Artplayer.ASPECT_RATIO` for default ratios `['default','4:3','16:9']`