Incompatible resource pack redness cannot be retextured

The bug

Much like how the black "currently selected" box used for resource packs and data packs cannot be retextured (MC-269443), the red rectangle indicating an incompatible pack cannot be retextured either, and appears to be hardcoded,

How to fix

Introduce a texture file for this effect (an opaque red rectangle with appropriate scaling mcmeta should suffice).