Support for allocating, copying and clearing separate array
layers and/or mip levels in VkImage objects. As part of that,
most functions that compute memory offsets or sizes now all
take mip levels and array layers into account.

Also, since this can cause many consecutive calls to the
blitter, the blitter object is now a VkImage member rather
than being create in each function, in order to better use
the blitter cache.

Bug b/119620767

Change-Id: Ib29b66cc936b0734c8173a1b8b5b9ef157fc7956
Reviewed-on: https://swiftshader-review.googlesource.com/c/23648Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>