OBJ_LOADER_DEMO: Remove "g" prefix from C++ side of the code

Since in the C++ scope they aren't global. Only in the shader scope.
OBJ_LOADER_DEMO: Create an extremely simple post process pixel shader

It just samples a HDR texture and outputs that color
OBJ_LOADER_DEMO: Render to HDR texture first, the PostProcess the HDR to the backbuffer

In preparation for future endeavors.
COMMON: Add a helper function to load a compute shader
COMMON: Add a ComputeShader class implementation
OBJ_LOADER_DEMO: Create a compute shader for Tiled Cull Final Gather
OBJ_LOADER_DEMO: Create a helper function for creating a heat map from a value
COMMON: Don't force the user to use MSAA if they use a specific overload

Check if the sample count is greater than 1 before forcing MSAA.
OBJ_LOADER_DEMO: Implement Tiled Culling Deferred Shading
OBJ_LOADER_DEMO: Fix formatting