Add missing `uint16` type registration for ops `CropAndResize`/`CropAndResizeGradBoxes` (#13812)

* Add missing `uint16` type registration for ops `CropAndResize`/`CropAndResizeGradBoxes`

This fix adds missing `uint16` type registration in `image_ops.cc`
for `CropAndResize` and `CropAndResizeGradBoxes`.

The kernel of `uint16` is available for `CropAndResize` and `CropAndResizeGradBoxes`
though it is missing in `image_ops.cc`. This fix addresses this issue.

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Add incomplete test cases for `CropAndResize`

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>