feat: add danmuku plugin documentation and i18n setup

- Created a new documentation file for the danmuku plugin with interactive code execution.
- Added comprehensive i18n setup instructions, including default language settings, language imports, and examples for adding and modifying languages.
- Introduced a test file to verify the integration of the danmuku plugin.

docs/esm.html

@@ -15,8 +15,8 @@
     <script type="importmap">
     {
         "imports": {
-            "artplayer": "/compiled/artplayer.esm.js",
-            "artplayer-plugin-danmuku": "/compiled/artplayer-plugin-danmuku.esm.js"
+            "artplayer": "/compiled/artplayer.mjs",
+            "artplayer-plugin-danmuku": "/compiled/artplayer-plugin-danmuku.mjs"
         }
     }
     </script>