Implement accessing textures through an index. It uses the same
interface as OpenGL, the main difference is that Vulkan bindings are
forced to be arrayed (the binding index doesn't change for stacked
textures in SPIR-V).
This abstractio represents the state of the 3D engine at a given draw.
Instead of changing individual bits of the pipeline how it's done in
APIs like D3D11, OpenGL and NVN; on Vulkan we are forced to put
everything together into a single, immutable object.
It takes advantage of the few dynamic states Vulkan offers.
