Improvements over Veldrid

[xoofx]

There are several pull-requests and issues raised on Veldrid.

Some are important bug fixes and improvements that I might want to integrate. Work should be more manageable as I only have to manage Vulkan.

Need to take the time to list here which one I would like to add to my list. For now for the PR:

• Avoid boxing allocations in blend attachment equality function veldrid/veldrid#500 (Fixed by 79dd2b2)
• Added lock to prevent race condition veldrid/veldrid#495 (Fixed by 81240a9)
• Added Vulkan support for copying depth textures veldrid/veldrid#462 (Fixed by d49b341)
• [Vk] Increment resource refs immediately veldrid/veldrid#450 (Fixed by 13289aa)
• [Vulkan] Add a custom equality comparer for ResourceRefCount veldrid/veldrid#406 (Fixed below)
• [Vulkan] Replaced ResourceRefCount with VkRefCountManager veldrid/veldrid#396 (Fixed by 75fe7d0 and 3e3b31c)
• [Vulkan] Improved memory allocator veldrid/veldrid#368 (Fixed by 1593f0f)
• Add ability to choose Vulkan device on multi GPU systems veldrid/veldrid#430 (Fixed by 1593f0f)
• [Vulkan] Vulkan binds incorrectly descriptor sets with dynamicOffsets when using two non contiguous resource sets veldrid/veldrid#387 (Fixed by e6b89d3)
• Add swapchain readback support veldrid/veldrid#363
• Add constant and slope-scaled depth bias options. veldrid/veldrid#357
• Allow automatic disposals of objects veldrid/veldrid#350

Whenever possible, add tests, as it was quite valuable to have already tests in Veldrid to double check the migration to XenoAtom.Interop.vulkan.

List of things I would like to improve:

• First pass of adding support for Nullable reference types (fixed via 9f4a801)
• Simplify code for image layout transitions (via 4980977)
• Improve debugging layers, switch to VK_EXT_debug_utils (via 52cf1eb)
• Add support for multiple GPU (e.g discrete and iGPU)
• Add better support to activate validation layers (there are currently warnings)
• Some cleanup of the code
• Use more modern C# features (Mostly Span and maybe some new C# 12 language features)
• Improve further memory allocator - using a TLSF/VMA like allocator (Fixed by New Vulkan memory allocator #2)
• Improve management of descriptor sets, see Optimizing Vulkan descriptors sets management #3
• Reduce allocations
• Once done, might promote XenoAtom.Interop.vulkan to a stable 1.0.0 as its integration looks good here