block_util, vhdx: vhdx crate integration with the cloud hypervisor

vhdx_sync.rs in block_util implements traits to represent the vhdx
crate as a supported block device in the cloud hypervisor. The vhdx
is added to the block device list in device_manager.rs at the vmm
crate so that it can automatically detect a vhdx disk and invoke the
corresponding crate.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Signed-off-by: Fazla Mehrab <akm.fazla.mehrab@intel.com>

Cargo.toml

@@ -78,6 +78,7 @@ members = [
     "qcow",
     "rate_limiter",
     "vfio_user",
+    "vhdx",
     "vhost_user_backend",
     "vhost_user_block",
     "vhost_user_net",