Strict Mode

[joedrago]

(Tracker issue for a future feature for myself.)

Add a strict boolean to avifDecoder which is very, very intolerant of imperfect AVIFs. Ideally, anything that ComplianceWarden would complain about would cause this decoder mode to fail.

Optional features to this mode would be precise output on exactly why the file was invalid (via some new mechanism), and/or actually force-decoding all frames inside during Parse once to ensure the payloads had valid content as well.

[y-guyon]

Done through 9b942c2 and #1611.