This class will not extend well to glTF so this cordons it off into the
filamesh namespace, which is an already-existing namespace that we use
for the things related to the filamesh file format.
For glTF we might create a new library with its own MeshReader so
this will mitigate confusion.
This is similar to its WebGL and Android counterparts, we simply did not
have a version for desktop. This uses resgen to package the model's
textures (albedo, normal, roughness, metallic, ao) into a library that
is linked only to this sample.
This is a good test because it applies multiple textures to the model.
Moreover Aaron was asking me for a C++ example that uses compressed
textures.
For now this selects the OpenGL backend. We can change it to use Vulkan
after we add support for 3-band formats to VulkanDriver.
