Memory management on iGPUs

[Tearnote]

When allocating eGPUonly buffers, vuk uses the device-local memory. This limits usage on integrated GPUs, which usually have very little dedicated memory, and a large amount of shared memory. As an example, the Ryzen 5900HX has 512MB device-local memory and 8GB shared memory.

A workaround is to always use eCPUtoGPU when running on an integrated GPU. It would be nice though if the vuk user didn't have to care about whether the host device is integrated or dedicated.