zink: use u_transfer_helper to split/merge interleaved depth/stencil formats

zink: use u_transfer_helper to split/merge interleaved depth/stencil formats

EXT_packed_depth_stencil adds GL_UNSIGNED_INT_24_8_EXT which is an interleaved format,
but vulkan spec states that reading/writing the corresponding format provides only the
D24 component, which requires that we perform separate operations for each component
using separate buffers

fixes mesa/mesa#3031

Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6266>