Added the ClearDepthStencilImage command and made some minor adjustments
to Image clear functions to make the depth and stencil clears work.

Passes all test in:
api.image_clearing.dedicated_allocation.clear_depth_stencil_image.*

Bug b/119620767

Change-Id: If4cfe6aa97b955c9bc7881bba89ab725897c36f9
Reviewed-on: https://swiftshader-review.googlesource.com/c/23728Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>