Fix extra-dark cracking animation on the sides of grass blocks

[muzikbike]

Request Description

Vanilla bug https://bugs.mojang.com/browse/MC-265667.

When breaking a grass block, the crack animation renders twice on each of the four side faces, making it appear noticeably darker than it otherwise would. This is without a doubt due to each side using two texture planes (one for the base and another for the overlay). This has happened ever since 14w06b, when grass blocks were made to use the new model system.

The expected results here would be for the cracking animation to only be displayed at the normal intensity.

A potential solution is provided in the comments of the linked ticket by Ismael Rosillo:
"It would be better to merge overlapping layers when building models on resource reload (so just one layer of the destroy texture is rendered) and cache them as baked faces at BakedModel.java on separate fields, and use them only when textures like "enchant_glint" and "destroy_progress" are being used. I made some tests yesterday and both MC-166101 and MC-265667 (this issue) seem to be fixed."