Convert ShellError::UnsupportedInput to named fields (#10971)

# Description

This is easy to do with rust-analyzer, but I didn't want to just pump
these all out without feedback.

Part of #10700

# User-Facing Changes

None

# Tests + Formatting

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

# After Submitting

N/A

---------

Co-authored-by: Stefan Holderbach <sholderbach@users.noreply.github.com>

crates/nu-command/src/bytes/at.rs

@@ -176,13 +176,12 @@ fn action(input: &Value, args: &Arguments, head: Span) -> Value {
         Value::Error { .. } => input.clone(),
 
         other => Value::error(
-            ShellError::UnsupportedInput(
-                "Only binary values are supported".into(),
-                format!("input type: {:?}", other.get_type()),
-                head,
-                // This line requires the Value::Error match above.
-                other.span(),
-            ),
+            ShellError::UnsupportedInput {
+                msg: "Only binary values are supported".into(),
+                input: format!("input type: {:?}", other.get_type()),
+                msg_span: head,
+                input_span: other.span(),
+            },
             head,
         ),
     }