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>

vhost_user_block/Cargo.toml

@@ -7,13 +7,12 @@ build = "../build.rs"
 
 [dependencies]
 argh = "0.1.9"
-block_util = { path = "../block_util" }
+block = { path = "../block" }
 env_logger = "0.10.0"
 epoll = "4.3.3"
 libc = "0.2.139"
 log = "0.4.17"
 option_parser = { path = "../option_parser" }
-qcow = { path = "../qcow" }
 vhost = { version = "0.7.0", features = ["vhost-user-slave"] }
 vhost-user-backend = "0.9.0"
 virtio-bindings = "0.2.0"

vhost_user_block/src/lib.rs

@@ -8,11 +8,14 @@
 //
 // SPDX-License-Identifier: (Apache-2.0 AND BSD-3-Clause)
 
-use block_util::{build_disk_image_id, Request, VirtioBlockConfig};
+use block::{
+    build_disk_image_id,
+    qcow::{self, ImageType, QcowFile},
+    Request, VirtioBlockConfig,
+};
 use libc::EFD_NONBLOCK;
 use log::*;
 use option_parser::{OptionParser, OptionParserError, Toggle};
-use qcow::{self, ImageType, QcowFile};
 use std::fs::File;
 use std::fs::OpenOptions;
 use std::io::Read;