glob with ../ prefix now works; (#10504)

Fixes #10503 
Also improves link to metacharacter help;

# Description
`glob` code was using pattern as provided by user. If that had leading
`..\`, `wax::Glob` is documented to treat them as literal chars to be
matched.
Fix is to use `wax::Glob.partition()` to split such invariant prefixes
off the pattern and tack them onto the working directory computed
separately.

Before
```
> ls ..
╭───┬───────┬──────┬──────┬───────────────╮
│ # │ name  │ type │ size │   modified    │
├───┼───────┼──────┼──────┼───────────────┤
│ 0 │ ../r1 │ dir  │  7 B │ 3 hours ago   │
│ 1 │ ../r2 │ dir  │  3 B │ a day ago     │
│ 2 │ ../r3 │ dir  │ 13 B │ 4 minutes ago │
╰───┴───────┴──────┴──────┴───────────────╯
> glob ../r*
╭────────────╮
│ empty list │
╰────────────╯
```
After 
```
> glob ../r*
╭───┬──────────────────────────────╮
│ 0 │ /home/bobhy/src/rust/work/r2 │
│ 1 │ /home/bobhy/src/rust/work/r1 │
│ 2 │ /home/bobhy/src/rust/work/r3 │
╰───┴──────────────────────────────╯
```

# User-Facing Changes
None

# Tests + Formatting
- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🟢 `toolkit test`
- 🟢 `toolkit test stdlib`

# After Submitting
<!-- If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
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---------

Co-authored-by: Darren Schroeder <343840+fdncred@users.noreply.github.com>

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

@@ -1,6 +1,8 @@
 use nu_test_support::fs::Stub::EmptyFile;
 use nu_test_support::nu;
 use nu_test_support::playground::Playground;
+use rstest::rstest;
+use std::path::{Path, PathBuf};
 
 #[test]
 fn empty_glob_pattern_triggers_error() {
@@ -118,3 +120,56 @@ fn glob_ignore_files() {
         );
     })
 }
+
+// clone of fs::create_file_at removing the parent panic, whose purpose I do not grok.
+pub fn create_file_at(full_path: impl AsRef<Path>) -> Result<(), std::io::Error> {
+    let full_path = full_path.as_ref();
+    std::fs::write(full_path, b"fake data")
+}
+
+// playground has root directory and subdirectories foo and foo/bar to play with
+// specify all test files relative to root directory.
+// OK to use fwd slash in paths, they're hacked to OS dir separator when needed (windows)
+#[rstest]
+#[case(".", r#"'*z'"#, &["ablez", "baker", "charliez"], &["ablez", "charliez"], "simple glob")]
+#[case(".", r#"'qqq'"#, &["ablez", "baker", "charliez"], &[], "glob matches none")]
+#[case("foo/bar", r#"'*[\]}]*'"#, &[r#"foo/bar/ab}le"#, "foo/bar/baker", r#"foo/bar/cha]rlie"#], &[r#"foo/bar/ab}le"#, r#"foo/bar/cha]rlie"#], "glob has quoted metachars")]
+#[case("foo/bar", r#"'../*'"#, &["foo/able", "foo/bar/baker", "foo/charlie"], &["foo/able", "foo/bar", "foo/charlie"], "glob matches files in parent")]
+#[case("foo", r#"'./{a,b}*'"#, &["foo/able", "foo/bar/baker", "foo/charlie"], &["foo/able", "foo/bar"], "glob with leading ./ matches peer files")]
+fn glob_files_in_parent(
+    #[case] wd: &str,
+    #[case] glob: &str,
+    #[case] ini: &[&str],
+    #[case] exp: &[&str],
+    #[case] tag: &str,
+) {
+    Playground::setup("glob_test", |dirs, sandbox| {
+        sandbox.within("foo").within("bar");
+        let working_directory = &dirs.test().join(wd);
+
+        for f in ini {
+            create_file_at(dirs.test().join(f)).expect("couldn't create file");
+        }
+
+        let actual = nu!(
+            cwd: working_directory,
+            r#"glob {} | sort | str join " ""#,
+            glob
+        );
+
+        let mut expected: Vec<String> = vec![];
+        for e in exp {
+            expected.push(
+                dirs.test()
+                    .join(PathBuf::from(e)) // sadly, does *not" convert "foo/bar" to "foo\\bar" on Windows.
+                    .to_string_lossy()
+                    .to_string(),
+            );
+        }
+
+        let expected = expected
+            .join(" ")
+            .replace('/', std::path::MAIN_SEPARATOR_STR);
+        assert_eq!(actual.out, expected, "\n  test: {}", tag);
+    });
+}