Add modulo operator and simplify in/not-in (#2505)

crates/nu-cli/tests/commands/math/mod.rs

@@ -161,6 +161,18 @@ fn parens_precedence() {
     assert_eq!(actual.out, "12");
 }
 
+#[test]
+fn modulo() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            = 9 mod 2
+        "#
+    ));
+
+    assert_eq!(actual.out, "1");
+}
+
 #[test]
 fn duration_math() {
     let actual = nu!(