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>

fuzz/fuzz_targets/linux_loader_cmdline.rs

@@ -9,7 +9,8 @@
 #![no_main]
 
 use libfuzzer_sys::fuzz_target;
-use vm_memory::{bitmap::AtomicBitmap, GuestAddress};
+use vm_memory::bitmap::AtomicBitmap;
+use vm_memory::GuestAddress;
 
 type GuestMemoryMmap = vm_memory::GuestMemoryMmap<AtomicBitmap>;