Video support

This patch adds basic video support with a scrubber, volume control and ability to set it on repeat

Desktop	Mobile

TODO:

• Put VideoPlayer into a loader/add back images
• Make it work properly with the thumbnail bar
• Ensure keyboard/screenreader support
• Make it work with the slideshow
• Make sure it looks nice
• Add preview thumbnails (out of scope)
• Add video to share dialog's MIME types
• Add video to desktop's MIME types
• ???
• Celebrate the merge 🥳