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/thread_helper.rs

@@ -3,19 +3,15 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 
-use std::{
-    panic::AssertUnwindSafe,
-    thread::{self, JoinHandle},
-};
+use std::panic::AssertUnwindSafe;
+use std::thread::{self, JoinHandle};
 
 use seccompiler::{apply_filter, SeccompAction};
 use vmm_sys_util::eventfd::EventFd;
 
-use crate::{
-    epoll_helper::EpollHelperError,
-    seccomp_filters::{get_seccomp_filter, Thread},
-    ActivateError,
-};
+use crate::epoll_helper::EpollHelperError;
+use crate::seccomp_filters::{get_seccomp_filter, Thread};
+use crate::ActivateError;
 
 pub(crate) fn spawn_virtio_thread<F>(
     name: &str,