ENH: added texture management and IBL to the Vulkan renderer

Data/IBL/roomBRDF.png.sha512

Data/IBL/roomIrradiance.dds.sha512

Data/IBL/roomRadiance.dds.sha512

Examples/Sandbox/CMakeLists.txt

Source/Materials/imstkRenderMaterial.h

Source/Materials/imstkTexture.h

.../VulkanRenderer/PostProcessing/imstkVulkanPostProcess.cpp

...ng/VulkanRenderer/PostProcessing/imstkVulkanPostProcess.h

...enderer/PostProcessing/imstkVulkanPostProcessingChain.cpp

...nRenderer/PostProcessing/imstkVulkanPostProcessingChain.h

...lkanRenderer/RenderDelegate/imstkVulkanRenderDelegate.cpp

...VulkanRenderer/RenderDelegate/imstkVulkanRenderDelegate.h

.../VulkanRenderer/VulkanShaders/PostProcessing/ao_frag.frag

...haders/PostProcessing/bilateral_blur_horizontal_frag.frag

...nShaders/PostProcessing/bilateral_blur_vertical_frag.frag

...er/VulkanShaders/PostProcessing/bloom_threshold_frag.frag

...er/VulkanShaders/PostProcessing/depth_downscale_frag.frag

...ndering/VulkanRenderer/VulkanShaders/mesh/decal_frag.frag

...ndering/VulkanRenderer/VulkanShaders/mesh/depth_frag.frag

...endering/VulkanRenderer/VulkanShaders/mesh/mesh_frag.frag