AVIF 10/12-bit support

[WerctFourth]

Describe your suggested feature

Mihon can't render high bit depth (more than 8 per channel) AVIFs (tested on the latest beta 0.16.5.6740).
It has no problem displaying 16-bit grayscale/48-bit RGB PNGs though.

Update 1:
Lossy and lossless JpegXLs from a 16/48 bit source do work.

Update 2:
As far as I can see, Mihon uses dav1d decoder for AVIF through libimagedecoder, and it's forced to compile with support of only 8 bits decoding: link
Maybe removing -Dbitdepths=8 is all what's needed to make them work.

Update 3:
I tried to compile an apk without this option and can confirm, 10 and 12-bit AVIFs started working. Libimagedecoder size increased from 4 971 248 bytes to 5 190 416 (219 168 bytes delta) for ARM64, so it's not a big concern I think.
Link to APK (ARM64), if needed.

Other details

No response

Acknowledgements

• I have searched the existing issues and this is a new ticket, NOT a duplicate or related to another open or closed issue.
• I have written a short but informative title.
• I have updated the app to version 0.16.5.
• I will fill out all of the requested information in this form.

[AntsyLich]

So are you making a pr or what?