feat: make to nuon raw option remove all white space (#15609)

# Description
Fixes #9942

This adds a new `--minified` flag to `to nuon` which removes all
possible white space. I added an example test to demonstrate the
functionality.

# User-Facing Changes

New flag becomes available to the user.

crates/nu-command/tests/commands/headers.rs

@@ -36,7 +36,7 @@ fn headers_handles_missing_values() {
         "
             [{x: a, y: b}, {x: 1, y: 2}, {x: 1, z: 3}]
             | headers
-            | to nuon --raw
+            | to nuon
         "
     ));