Make optional cell paths work with reject (#8697)

This PR makes `?` work with `reject`. For example:

```bash
> {} | reject foo
Error: nu:🐚:column_not_found

  × Cannot find column
   ╭─[entry #2:1:1]
 1 │ {} | reject foo
   ·      ───┬── ─┬─
   ·         │    ╰── cannot find column 'foo'
   ·         ╰── value originates here
   ╰────

> {} | reject foo?
╭──────────────╮
│ empty record │
╰──────────────╯
```

This was prompted by [a user
question](https://discord.com/channels/601130461678272522/614593951969574961/1091466428546306078).
I would like to get this in for 0.78, I think it's low-risk and I want
the `?` feature to be as polished as possible for its debut.

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

@@ -147,3 +147,24 @@ fn reject_large_vec_with_two_identical_elements() {
     assert!(actual.out.contains("100"));
     assert!(actual.out.contains('2'));
 }
+
+#[test]
+fn reject_optional_column() {
+    let actual = nu!("{} | reject foo? | to nuon");
+    assert_eq!(actual.out, "{}");
+
+    let actual = nu!("[{}] | reject foo? | to nuon");
+    assert_eq!(actual.out, "[{}]");
+
+    let actual = nu!("[{} {foo: 2}] | reject foo? | to nuon");
+    assert_eq!(actual.out, "[{}, {}]");
+
+    let actual = nu!("[{foo: 1} {foo: 2}] | reject foo? | to nuon");
+    assert_eq!(actual.out, "[{}, {}]");
+}
+
+#[test]
+fn reject_optional_row() {
+    let actual = nu!("[{foo: 'bar'}] | reject 3? | to nuon");
+    assert_eq!(actual.out, "[[foo]; [bar]]");
+}