Publicly declare all file types supported by the media library

The VLC-iOS app should expose all the file extensions supported by the media library, so it can actually receive all those files other apps. For instance, when you have a "movie.264" right now in Share.It, you cannot use the share sheet to copy it to VLC because iOS is not aware that VLC supports this file type.

You can find all the extensions here: https://code.videolan.org/videolan/medialibrary/blob/master/src/MediaLibrary.cpp#L106