Add rustfmt.toml for explicit styling (#348)

* Propose an explicit .rustfnt.toml
Use 2024 style, 4 spaces for tabs and epand the default width a tad

* Auto-format the existing code with new rules

input-capture/src/dummy.rs

@@ -1,6 +1,6 @@
 use std::f64::consts::PI;
 use std::pin::Pin;
-use std::task::{ready, Context, Poll};
+use std::task::{Context, Poll, ready};
 use std::time::Duration;
 
 use async_trait::async_trait;