Screen reader-friendly errors (#10122)

- Hopefully closes #10120  

# Description

This PR adds a new config item, `error_style`. It will render errors in
a screen reader friendly mode when set to `"simple"`. This is done using
`miette`'s own `NarratableReportHandler`, which seamlessly replaces the
default one when needed.

Before:
```
Error: nu:🐚:external_command

  × External command failed
   ╭─[entry #2:1:1]
 1 │ doesnt exist
   · ───┬──
   ·    ╰── executable was not found
   ╰────
  help: No such file or directory (os error 2)
```

After:
```
Error: External command failed
    Diagnostic severity: error
Begin snippet for entry #4 starting at line 1, column 1

snippet line 1: doesnt exist
    label at line 1, columns 1 to 6: executable was not found
diagnostic help: No such file or directory (os error 2)
diagnostic code: nu:🐚:external_command

```

## Things to be determined

- ~Review naming. `errors.style` is not _that_ consistent with the rest
of the code. Menus use a `style` record, but table rendering mode is set
via `mode`.~ As it's a single config, we're using `error_style` for now.
- Should this kind of setting be toggable with one single parameter?
`accessibility.no_decorations` or similar, which would adjust the style
of both errors and tables accordingly.

# User-Facing Changes

No changes by default, errors will be rendered differently if
`error_style` is set to `simple`.

# Tests + Formatting
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# After Submitting

There's a PR updating the docs over here
https://github.com/nushell/nushell.github.io/pull/1026

crates/nu-protocol/tests/test_config.rs

@@ -49,3 +49,58 @@ fn filesize_format_auto_metric_false() {
     let actual = nu!(nu_repl_code(code));
     assert_eq!(actual.out, r#"["1.9 MiB", "1.9 GiB", "1.8 TiB"]"#);
 }
+
+#[test]
+fn fancy_default_errors() {
+    let actual = nu!(nu_repl_code(&[
+        r#"def force_error [x] {
+        let span = (metadata $x).span;
+        error make {
+            msg: "oh no!"
+            label: {
+                text: "here's the error"
+                start: $span.start
+                end: $span.end
+            }
+        }
+    }"#,
+        r#"force_error "My error""#
+    ]));
+
+    assert_eq!(
+        actual.err,
+        "Error:   \u{1b}[31m×\u{1b}[0m oh no!\n   ╭─[\u{1b}[36;1;4mline1\u{1b}[0m:1:1]\n \u{1b}[2m1\u{1b}[0m │ force_error \"My error\"\n   · \u{1b}[35;1m            ─────┬────\u{1b}[0m\n   ·                  \u{1b}[35;1m╰── \u{1b}[35;1mhere's the error\u{1b}[0m\u{1b}[0m\n   ╰────\n\n\n"
+    );
+}
+
+#[test]
+fn narratable_errors() {
+    let actual = nu!(nu_repl_code(&[
+        r#"$env.config = { error_style: "plain" }"#,
+        r#"def force_error [x] {
+        let span = (metadata $x).span;
+        error make {
+            msg: "oh no!"
+            label: {
+                text: "here's the error"
+                start: $span.start
+                end: $span.end
+            }
+        }
+    }"#,
+        r#"force_error "my error""#,
+    ]));
+
+    assert_eq!(
+        actual.err,
+        r#"Error: oh no!
+    Diagnostic severity: error
+Begin snippet for line2 starting at line 1, column 1
+
+snippet line 1: force_error "my error"
+    label at line 1, columns 13 to 22: here's the error
+
+
+"#,
+    );
+}