misc: Further improve imports styling

By introducing `imports_granularity="Module"` format strategy,
effectively groups imports from the same module into one line or block,
improving maintainability and readability.

Signed-off-by: Ruoqing He <heruoqing@iscas.ac.cn>

virtio-devices/src/mem.rs

@@ -15,13 +15,11 @@
 // limitations under the License.
 
 use std::collections::BTreeMap;
-use std::io;
 use std::mem::size_of;
 use std::os::unix::io::{AsRawFd, RawFd};
-use std::result;
 use std::sync::atomic::AtomicBool;
-use std::sync::mpsc;
-use std::sync::{Arc, Barrier, Mutex};
+use std::sync::{mpsc, Arc, Barrier, Mutex};
+use std::{io, result};
 
 use anyhow::anyhow;
 use seccompiler::SeccompAction;
@@ -37,15 +35,14 @@ use vm_migration::protocol::MemoryRangeTable;
 use vm_migration::{Migratable, MigratableError, Pausable, Snapshot, Snapshottable, Transportable};
 use vmm_sys_util::eventfd::EventFd;
 
-use super::Error as DeviceError;
 use super::{
-    ActivateError, ActivateResult, EpollHelper, EpollHelperError, EpollHelperHandler, VirtioCommon,
-    VirtioDevice, VirtioDeviceType, EPOLL_HELPER_EVENT_LAST, VIRTIO_F_VERSION_1,
+    ActivateError, ActivateResult, EpollHelper, EpollHelperError, EpollHelperHandler,
+    Error as DeviceError, VirtioCommon, VirtioDevice, VirtioDeviceType, EPOLL_HELPER_EVENT_LAST,
+    VIRTIO_F_VERSION_1,
 };
 use crate::seccomp_filters::Thread;
 use crate::thread_helper::spawn_virtio_thread;
-use crate::{GuestMemoryMmap, GuestRegionMmap};
-use crate::{VirtioInterrupt, VirtioInterruptType};
+use crate::{GuestMemoryMmap, GuestRegionMmap, VirtioInterrupt, VirtioInterruptType};
 
 const QUEUE_SIZE: u16 = 128;
 const QUEUE_SIZES: &[u16] = &[QUEUE_SIZE];