v3.6.8 : Performance and detection upgrades

Many small new fixes were made in this version :

• Updated the MIME detection method settings as it did not work with mp4 videos. Even when enabled, mp4 videos were detected only based on the URL, as the manipulation I was doing on the mime type resulted in it being listed as "mp" instead of "mp4" which the add-on wouldn't find
• Updated the encoding of file names in the media list, so media with special characters in their name will show the correct characters instead of an URL encoded version
• Updated the media previewer with a new snackbar message, support for translations
• In the media previewer, the extension will first try to check if the media playback is supported natively by the browser for the media's specific file format before attempting to use an external library to play it
• Updated the detection to cache all media with a mime type starting with audio/ or video/ , being case insensitive.
• Added a message when the media list is loading