Create a special error variant for "device removed"

[MarijnS95]

As we've seen in #262 ERROR_DEVICE_REMOVED can also be raised out of resource creation functions (on Dx12) which gpu-allocator calls. We have some custom logic to run on specifically those errors, but gpu-allocator currently only returns them back in opaque Internal(String) variant leading to ugly string-compares, when we'd rather match on a stable DeviceRemoved variant that is mapped from ERROR_DEVICE_REMOVED.