PBR_DEMO/COMMON: static_cast size_t to uint

In cases where the code assumes size to be a uint
COMMON: Move hlsl_util.hlsli under Common
PBR_DEMO: Remove unused shader
PBR_DEMO: Remove shader_build_chain.json

Since it's not being used
PBR_DEMO: Convert GBufferPS to use the new material system
PBR_DEMO: Add an example material and a pine wood material
DOCUMENTATION: Fix colon formatting