AVIF support photoe Elementary OS 8

[ghost]

Problem

seems to not have AVIF support in the early builds of Elementary OS 8.

Proposal

Add AVIF support for the app "photos" in Elementary OS 8.

Prior Art (Optional)

Shotwell does support AVIF.

[zeebok]

One part of the problem is that I am not seeing support for that file format yet in gstreamer, which we make use of. We also plan to do a big rewrite of Photos from the ground up so AVIF support may need to wait until the release of that if gstreamer is is going to take a bit to update.