Add new operators has and not-has (#14841)

# Description
This PR add 2 new operators, `has` and `not-has`. They are basically
`in` and `not-in` with the order of operands swapped.

Motivation for this was the awkward way of searching for rows that
contain an item using `where`

```nushell
[[name, children]; [foo, [a, b, c]], [bar [d, e, f]]]
| where ("e" in $it.children)
```
vs
```nushell
[[name, children]; [foo, [a, b, c]], [bar [d, e, f]]]
| where children has "e"
``` 

# User-Facing Changes
Added `has` and `not-has` operators, mirroring `in` and `not-in`.

# Tests + Formatting

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

# After Submitting

crates/nu-cli/src/completions/operator_completions.rs

@@ -107,10 +107,14 @@ impl Completer for OperatorCompletion {
                 ("not-in", "Is not a member of (doesn't use regex)"),
             ],
             Expr::FullCellPath(path) => match path.head.expr {
-                Expr::List(_) => vec![(
-                    "++",
-                    "Concatenates two lists, two strings, or two binary values",
-                )],
+                Expr::List(_) => vec![
+                    (
+                        "++",
+                        "Concatenates two lists, two strings, or two binary values",
+                    ),
+                    ("has", "Contains a value of (doesn't use regex)"),
+                    ("not-has", "Does not contain a value of (doesn't use regex)"),
+                ],
                 Expr::Var(id) => get_variable_completions(id, working_set),
                 _ => vec![],
             },