Support native AAC for audio download (m4a)

[highbaser]

describe the feature you'd like to see

Under https://cobalt.tools/settings/audio only best, mp3, ogg, wav, opus are supported. All formats except best involve a conversion, which leads to quality loss because of converting a lossy audio track with another lossy codec. Of course users who don't want quality loss can still select "best", but on Youtube this translates to OPUS@48kHz which is isn't a well-supported format by video/audio editors and dedicated (hardware) MP3/MP4 players and gets resampled by Youtube to 48 kHz, while the majority of uploads (e.g.) songs are still sampled @ 44.1 kHz. Youtube still offers a separate AAC audio track under format tag 140 @ ~128 kbit/s and 44.1 kHz. That could be packed into an m4a and offered for download.

additional context

No response