Ratelimit save command progress bar updates (#14075)

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# Description
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Currently, the `save -p` command updates the progress animation each
time any data is written. This PR rate limits the animation so it
doesn't play as fast.

Here's an asciinema of [current
behavior](https://asciinema.org/a/8RWrWTozQSceqx6tYY7kzblqj) and
[proposed behavior](https://asciinema.org/a/E1pi0gMwMwFcxVHOy9Fv1Kk6R).

# User-Facing Changes

* `save -p` progress bar has a smoother animation

# Tests + Formatting

- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🟢 `toolkit test`
- 🟢 `toolkit test stdlib`

# After Submitting
N/A

crates/nu-command/src/filesystem/save.rs

@@ -12,6 +12,7 @@ use std::{
     io::{self, BufRead, BufReader, Read, Write},
     path::{Path, PathBuf},
     thread,
+    time::{Duration, Instant},
 };
 
 #[derive(Clone)]
@@ -482,7 +483,7 @@ fn stream_to_file(
 
         let mut bar = progress_bar::NuProgressBar::new(known_size);
 
-        // TODO: reduce the number of progress bar updates?
+        let mut last_update = Instant::now();
 
         let mut reader = BufReader::new(source);
 
@@ -499,7 +500,10 @@ fn stream_to_file(
                     let len = buf.len();
                     reader.consume(len);
                     bytes_processed += len as u64;
+                    if last_update.elapsed() >= Duration::from_millis(75) {
                         bar.update_bar(bytes_processed);
+                        last_update = Instant::now();
+                    }
                 }
                 Err(e) if e.kind() == io::ErrorKind::Interrupted => continue,
                 Err(e) => break Err(e),