block: merge qcow, vhdx and block_util into block crate

This commit merges crates `qcow`, `vhdx` and `block_util` into the
crate `block`, which can allow `qcow` to use functions from `block_util`
without introducing a circular crate dependency.

This commit is based on crosvm implementation:
https://chromium.googlesource.com/crosvm/crosvm/+/f2eecc4152eca8d395566cffa2c102ec090a152d

Signed-off-by: Yu Li <liyu.yukiteru@bytedance.com>

block/Cargo.toml

@@ -0,0 +1,27 @@
+[package]
+name = "block"
+version = "0.1.0"
+edition = "2021"
+authors = ["The Cloud Hypervisor Authors", "The Chromium OS Authors"]
+
+[features]
+default = []
+io_uring = ["dep:io-uring"]
+
+[dependencies]
+byteorder = "1.4.3"
+crc32c = "0.6.3"
+io-uring = { version = "0.5.13", optional = true }
+libc = "0.2.139"
+log = "0.4.17"
+remain = "0.2.6"
+smallvec = "1.10.0"
+thiserror = "1.0.40"
+uuid = { version = "1.3.4", features = ["v4"] }
+versionize = "0.1.10"
+versionize_derive = "0.1.4"
+virtio-bindings = { version = "0.2.0", features = ["virtio-v5_0_0"] }
+virtio-queue = "0.8.0"
+vm-memory = { version = "0.11.0", features = ["backend-mmap", "backend-atomic", "backend-bitmap"] }
+vm-virtio = { path = "../vm-virtio" }
+vmm-sys-util = "0.11.0"