[SYCL][CUDA] PI API Image Support for CUDA (#1954)

Updates the CUDA `piMem` implementation to support images. 

Provides implementations of the PI API `piMemImageCreate`, `piEnqueueMemImageRead`, `piEnqueueMemImageWrite` and `piEnqueueMemImageCopy` functions for CUDA backends.

The implementation required changes to the `_pi_mem` struct so that it supports both images and buffers, so changes were necessary across many CUDA `piMem*` function implementations.

Author: nyalloc