Defined interface for virtual allocator:
Defined interface for virtual allocator:

VmaVirtualBlockCreateFlagBits, VmaVirtualBlockCreateFlags, VmaVirtualBlockCreateInfo, VmaVirtualAllocationCreateInfo, VmaVirtualBlock, all necessary functions.
Implementation: added VmaVirtualBlock_T. Not working for now.

GPUOpen-LibrariesAndSDKs/VulkanMemoryAllocator,GPUOpen-LibrariesAndSDKs/VulkanMemoryAllocator,GPUOpen-LibrariesAndSDKs/VulkanMemoryAllocator