[Enhancement]: Support more m4b tags

[DarkShortie]

Describe the feature/enhancement

I prefer storing all metadata in the file itself instead of using "companion files" or folder / filenames and have a whole audiobook in one file.

Therefore I'm using the m4b format and I have activated the setting "Scanner prefer audio metadata".

Then I tried to to set the metadata according to the mp4 metadata fields and what is described here https://www.audiobookshelf.org/docs#book-audio-metadata

I've also set some additional tags which are used by the aaxc format from Audible (which is also just a mp4 container) and it would be great if those custom tags could also be supported by audiobookshelf.

Not all tags are working, is there a list which mp4 tags are mapped to which audiobookshelf data field? For the mp4 tags it would be could to know the atom names instead of what is displayed in different tools because the friendly name also differs between the different tools.

This is are my results and enhancement requests so far:

audiobookshelf	mp4 atom	Note
Author	aArt	working
Title	©alb	working
Subtitle	subt	not working, working atom available? If not please implement, custom atom
Publisher	cprt	not working, working atom available? If not please implement, offical atom
Publisher	©pub	custom atom used by Audible aaxc, please implement
Publish Year	©day	working
Publish Year	rldt	custom atom used by Audible aaxc, this contains a complete date in the format yyyy-mm-dd and could enhance the data in audiobookshelf
Narrator	©wrt	working
Narrator	©nrt	custom atom used by Audible aaxc, please implement
Description	©des	not working, working atom available? If not please implement, offical atom
Genres	©gen	working
Series	tvsh	not working, working atom available? If not please implement, custom atom
Volume Number	tves	not working, working atom available? If not please implement, custom atom
Language	lang	not working, working atom available? If not please implement, custom atom
ASIN	asin	not working, please implement, custom atom