Needed to fix T61196, supporting clipped back-buffer in the 3D view
which is done outside the draw module.
It was also inconvenient having DRW_shader_* versions of GPU_shader_*
API calls.
- Clipping distances are now supported as a shader configuration
for builtin shaders.
- Add shader config argument when accessing builtin shaders.
- Move GPU_shader_create_from_arrays() from DRW to GPU.
dbd7f36da8