Vulkan doesn't have a conversion from uint32_t/int32_t to float. It does
have conversions from 16/8 bits. Main reason is that Vulkan expects that
there is no benefit when converting 32 bits from one type to the other
and should be solved by passing the right data type.
In Blender however this isn't the case as there are benefits on other
GPU backends (OpenGL for example).
This PR adds helper function to check if conversion is needed and
perform any conversions in place. It also implements the function to
upload vertex buffers to the GPU.
Jeroen Bakker