Reorganize symphonia's feature flags

[Keinsleif]

Symphonia's feature flags are separated into format flags and codec flags.
Current symphonia flags wrapped in rodio is a mixture of these two types.

This PR reorganize these flags to format-based (extension-based like).
The flags are separated by format and each flags are contains possible codec flags in the format.

Detail

• symphonia-aac
  not changed

• symphonia-flac
  not changed

• symphonia-isomp4
  mpa(mp3+mp2+mp1), aac, alac flags are added.

• symphonia-mp3
  not changed

• symphonia-ogg
  vorbis, flac, pcm flags are added

• symphonia-vorbis
  deleted
  vorbis flag is codec name in symphonia
  Standalone vorbis format is not general as far as I could find.

• symphonia-wav
  not changed

• symphonia-alac
  not changed

• symphonia-aiff
  not changed

• symphonia-caf
  added
  Core Audio Format support
  With pcm, adpcm, mpa(mp3+mp2+mp1), aac, alac flags

• symphonia-mkv
  added
  mkv (actually mka) and webm support
  With aac, mpa, vorbis, pcm, flac, alac flags

Note:
Currently, symphonia is not support opus codec.
These formats can contain opus format.
isomp4, ogg, caf, mkv(webm)

[dvdsk]

First off all thanks for helping out!

D note some of this work is underway in PR731. I do however not think @roderickvd minds you taking this on instead.

Please see the related discussion in: #731