Integrate #4019 updateImageDecodePriority - Avoid Long Face Loop

[marchcat]

Description

See #4019.

[AtlasLinden]

Scenes with more than 1024 faces has textures loading in a different (and nicer) order. See the beginning of the clips attached below of a previous build (7.1.15.15596336374) and the tested GLTF Import build (7.1.14.15976006598). The textures in this scene finish loading almost 20 seconds faster than the previous build too!
Note that this difference is only observed on Windows. MacOS appears to not show any difference at all upon comparing these two builds.

As far as scenes with less than 1024 faces, no clear difference is yet to be spotted.

It will be good to see if there's any user feedback regarding this when this rolls out to beta or default release.
For now this passes QA.
Verified on Second Life Project 7.1.14.15976006598 (GLTF Mesh Import) on Win11/MacOS

7.1.15: https://gyazo.com/e8b66e8ea908ee0d733904fbcf21a438
GLTF import: https://gyazo.com/949c6f4f83a016656d5a694726e28d1e