This commit adds the asynchronous support for fixed VHD disk files.
It introduces FixedVhd as a new ImageType, moving the image type
detection to the block_util crate (instead of qcow crate).
It creates a new vhd module in the block_util crate in order to handle
VHD footer, following the VHD specification.
It creates a new fixed_vhd_async module in the block_util crate to
implement the asynchronous version of fixed VHD disk file. It relies on
io_uring.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
