Support video and audio syntax

DokuWiki supports displaying audio and video files with the same syntax as for images. This includes support for multiple alternative formats and thumbnails. See https://www.dokuwiki.org/wiki:syntax#supported_media_formats for details. This is currently not supported in the importer, it treats all files as images.

XWiki currently doesn't support this so we would need to see what the closest equivalent in XWiki is (like some macro) or the importer needs to generate raw HTML.