Refactor the overall module to place the unified vorbis tags into a single package called `vorbis`. Also re-intoduce the vorbis tags in their original `flac` module, but deprecate them.
Move all picture and vorbis frame parsing into a new xiph module. This commit also adds cover frame parsing from vorbis comments as well.
PiperOrigin-RevId: 407379522
#minor-release PiperOrigin-RevId: 373351935