glTF texture loading

[sgmq0]

Description

Texture loading!! Woo!!!!

Instancer now supports glTF loading with multiple textures as well as transparent textures.

However, this comes with some caveats:

• Due to the limitations of WebGPU, all textures must be the same size. Otherwise, issues will be encountered.
• The glTF loader assumes that the id of each material is also its index in the material array.