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>

arch/src/lib.rs

@@ -11,9 +11,8 @@
 extern crate log;
 
 use std::collections::BTreeMap;
-use std::fmt;
-use std::result;
 use std::sync::Arc;
+use std::{fmt, result};
 
 use serde::{Deserialize, Serialize};
 use thiserror::Error;