Add helper method to check whether ctrl+c was pressed, adopt it (#7482)

I've been working on streaming and pipeline interruption lately. It was
bothering me that checking ctrl+c (something we want to do often) always
requires a bunch of boilerplate like:
```rust
use std::sync::atomic::Ordering;

if let Some(ctrlc) = &engine_state.ctrlc {
     if ctrlc.load(Ordering::SeqCst) {
          ...
```
I added a helper method to cut that down to:

```rust
if nu_utils::ctrl_c::was_pressed(&engine_state.ctrlc) {
    ...
```

crates/nu-command/src/platform/dir_info.rs

@@ -2,7 +2,7 @@ use filesize::file_real_size_fast;
 use nu_glob::Pattern;
 use nu_protocol::{ShellError, Span, Value};
 use std::path::PathBuf;
-use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::atomic::AtomicBool;
 use std::sync::Arc;
 
 #[derive(Debug, Clone)]
@@ -106,13 +106,8 @@ impl DirInfo {
         match std::fs::read_dir(&s.path) {
             Ok(d) => {
                 for f in d {
-                    match ctrl_c {
-                        Some(ref cc) => {
-                            if cc.load(Ordering::SeqCst) {
-                                break;
-                            }
-                        }
-                        None => continue,
+                    if nu_utils::ctrl_c::was_pressed(&ctrl_c) {
+                        break;
                     }
 
                     match f {

crates/nu-command/src/platform/sleep.rs

@@ -6,7 +6,6 @@ use nu_protocol::{
     Type, Value,
 };
 use std::{
-    sync::atomic::Ordering,
     thread,
     time::{Duration, Instant},
 };
@@ -62,10 +61,8 @@ impl Command for Sleep {
                 break;
             }
 
-            if let Some(ctrlc) = ctrlc_ref {
-                if ctrlc.load(Ordering::SeqCst) {
-                    break;
-                }
+            if nu_utils::ctrl_c::was_pressed(ctrlc_ref) {
+                break;
             }
         }