Fix advanced subtitles shaping features

The macOS interface provides access to "freetype-color", "freetype-background-opacity", "freetype-background-color" and "freetype-outline-thickness" through a menu. To have the options take effect immediately, variables on the playlist singleton were created. This is no longer possible in VLC 4, so we need to find a work-around or drop the feature.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information