Blender Git Loki

DRW: Remove automatic bind locations and use hardcoded locations for textures

This cleanup use the recent changes in shader interface to allow querying
the binding location a texture should use.

This should aleviate all issue we have with texture state change recompiling
the shaders at drawtime.

All binds are now treated like persistent binds and will stick until a new
shading group bind a different shader. The only difference is that you can
still change it with a new subgroup or same shader shgroup.

Since unbinding can be heavy we only do it when using `--debug-gpu`.