Bindless image desc match ur

[cperkinsintel]

The bindless image image_descriptor does not have pitch/slice. We need that to properly create a ur_image_desc_t . Without it we'll never be able to support linear images that have aligned strides. There are also some older SYCL 1.2.1 defensive checks that will also block.

Added a unit test that demonstrates that these values correctly arrive at the UR.

Here is the ur_image_desc_t from ur_api.h in case anyone is wondering:

typedef struct ur_image_desc_t {
  /// [in] type of this structure, must be ::UR_STRUCTURE_TYPE_IMAGE_DESC
  ur_structure_type_t stype;
  /// [in][optional] pointer to extension-specific structure
  const void *pNext;
  /// [in][nocheck] memory object type
  ur_mem_type_t type;
  /// [in] image width
  size_t width;
  /// [in] image height
  size_t height;
  /// [in] image depth
  size_t depth;
  /// [in] image array size
  size_t arraySize;
  /// [in] image row pitch
  size_t rowPitch;
  /// [in] image slice pitch
  size_t slicePitch;
  /// [in] number of MIP levels, must be `0`
  uint32_t numMipLevel;
  /// [in] number of samples, must be `0`
  uint32_t numSamples;

} ur_image_desc_t;