Fix quoting in to nuon and refactor quoting functions (#14180)

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# Description
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This PR fixes the quoting and escaping of column names in `to nuon`.
Before the PR, column names with quotes inside them would get quoted,
but not escaped:

```nushell
> { 'a"b': 2 } | to nuon
{ "a"b": 2 }

> { 'a"b': 2 } | to nuon | from nuon
Error:   × error when loading nuon text
   ╭─[entry #1:1:27]
 1 │ { "a\"b": 2 } | to nuon | from nuon
   ·                           ────┬────
   ·                               ╰── could not load nuon text
   ╰────

Error:   × error when parsing nuon text
   ╭─[entry #1:1:27]
 1 │ { "a\"b": 2 } | to nuon | from nuon
   ·                           ────┬────
   ·                               ╰── could not parse nuon text
   ╰────

Error:   × error when parsing
   ╭────
 1 │ {"a"b": 2}
   ·          ┬
   ·          ╰── Unexpected end of code.
   ╰────

> [['a"b']; [2] [3]] | to nuon
[["a"b"]; [2], [3]]

> [['a"b']; [2] [3]] | to nuon | from nuon
Error:   × error when loading nuon text
   ╭─[entry #1:1:32]
 1 │ [['a"b']; [2] [3]] | to nuon | from nuon
   ·                                ────┬────
   ·                                    ╰── could not load nuon text
   ╰────

Error:   × error when parsing nuon text
   ╭─[entry #1:1:32]
 1 │ [['a"b']; [2] [3]] | to nuon | from nuon
   ·                                ────┬────
   ·                                    ╰── could not parse nuon text
   ╰────

Error:   × error when parsing
   ╭────
 1 │ [["a"b"]; [2], [3]]
   ·                   ┬
   ·                   ╰── Unexpected end of code.
   ╰────
```

After this PR, the quote is escaped properly:

```nushell
> { 'a"b': 2 } | to nuon
{ "a\"b": 2 }

> { 'a"b': 2 } | to nuon | from nuon
╭─────┬───╮
│ a"b │ 2 │
╰─────┴───╯

> [['a"b']; [2] [3]] | to nuon
[["a\"b"]; [2], [3]]

> [['a"b']; [2] [3]] | to nuon | from nuon
╭─────╮
│ a"b │
├─────┤
│   2 │
│   3 │
╰─────╯
```

The cause of the issue was that `to nuon` simply wrapped column names in
`'"'` instead of calling `escape_quote_string`.

As part of this change, I also moved the functions related to quoting
(`needs_quoting` and `escape_quote_string`) into `nu-utils`, since
previously they were defined in very ad-hoc places (and, in the case of
`escape_quote_string`, it was defined multiple times with the same
body!).

# User-Facing Changes
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`to nuon` now properly escapes quotes in column names.

# Tests + Formatting
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All tests pass, including workspace and stdlib tests.

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crates/nu-utils/src/lib.rs

@@ -4,6 +4,7 @@ mod deansi;
 pub mod emoji;
 pub mod filesystem;
 pub mod locale;
+mod quoting;
 mod shared_cow;
 pub mod utils;
 
@@ -18,6 +19,7 @@ pub use deansi::{
     strip_ansi_likely, strip_ansi_string_likely, strip_ansi_string_unlikely, strip_ansi_unlikely,
 };
 pub use emoji::contains_emoji;
+pub use quoting::{escape_quote_string, needs_quoting};
 pub use shared_cow::SharedCow;
 
 #[cfg(unix)]

crates/nu-utils/src/quoting.rs

@@ -0,0 +1,43 @@
+use fancy_regex::Regex;
+use once_cell::sync::Lazy;
+
+// This hits, in order:
+// • Any character of []:`{}#'";()|$,
+// • Any digit (\d)
+// • Any whitespace (\s)
+// • Case-insensitive sign-insensitive float "keywords" inf, infinity and nan.
+static NEEDS_QUOTING_REGEX: Lazy<Regex> = Lazy::new(|| {
+    Regex::new(r#"[\[\]:`\{\}#'";\(\)\|\$,\d\s]|(?i)^[+\-]?(inf(inity)?|nan)$"#)
+        .expect("internal error: NEEDS_QUOTING_REGEX didn't compile")
+});
+
+pub fn needs_quoting(string: &str) -> bool {
+    if string.is_empty() {
+        return true;
+    }
+    // These are case-sensitive keywords
+    match string {
+        // `true`/`false`/`null` are active keywords in JSON and NUON
+        // `&&` is denied by the nu parser for diagnostics reasons
+        // (https://github.com/nushell/nushell/pull/7241)
+        "true" | "false" | "null" | "&&" => return true,
+        _ => (),
+    };
+    // All other cases are handled here
+    NEEDS_QUOTING_REGEX.is_match(string).unwrap_or(false)
+}
+
+pub fn escape_quote_string(string: &str) -> String {
+    let mut output = String::with_capacity(string.len() + 2);
+    output.push('"');
+
+    for c in string.chars() {
+        if c == '"' || c == '\\' {
+            output.push('\\');
+        }
+        output.push(c);
+    }
+
+    output.push('"');
+    output
+}