Remove artplayer-plugin-liquid-glass plugin

- Deleted the plugin files including JavaScript, CSS, README, and type definitions.
- Removed references to the plugin from the documentation.
- Cleaned up the package structure by removing the .npmignore and package.json files related to the plugin.

docs/assets/js/common.js

@@ -62,7 +62,6 @@
       './assets/ts/artplayer-plugin-vast.d.ts',
       './assets/ts/artplayer-plugin-vtt-thumbnail.d.ts',
       './assets/ts/artplayer-plugin-document-pip.d.ts',
-      './assets/ts/artplayer-plugin-liquid-glass.d.ts',
       './assets/ts/artplayer-plugin-jassub.d.ts',
       './assets/ts/artplayer-proxy-canvas.d.ts',
       './assets/ts/artplayer-proxy-mediabunny.d.ts',