Add custom sample locations and coverage reduction modes

[devshgraphicsprogramming]

RenderpassIndependentPipeline

Figure out what the !"£% is this for and if its Nvidia only (if it is then !"£% it): https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VkPipelineCoverageModulationStateCreateInfoNV.html https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VkPipelineCoverageToColorStateCreateInfoNV.html

reduction modes: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VkCoverageReductionModeNV.html

just the array of locations: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VkSampleLocationEXT.html

Our Subpass struct

just the stuff about the grid, the sample per pixel count you can derive (I guess) https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VkSampleLocationsInfoEXT.html

[devshgraphicsprogramming]

A future task in the near future