Alias changes in upstream VMA

[M2-TE]

As per GPUOpen-LibrariesAndSDKs/VulkanMemoryAllocator#522, VMA will also supply a VulkanMemoryAllocator::Headers CMake target.
Once that is in, we can also create VulkanMemoryAllocator::Hpp and VulkanMemoryAllocator::HppModule here, similar to Vulkan-Hpp.