KCL: Add planeOf function to stdlib (#7643)

Gets the plane a face lies on, if any.

Closes #7642

rust/kcl-lib/src/simulation_tests.rs

@@ -3632,3 +3632,24 @@ mod non_english_identifiers {
         super::execute(TEST_NAME, true).await
     }
 }
+mod plane_of {
+    const TEST_NAME: &str = "plane_of";
+
+    /// Test parsing KCL.
+    #[test]
+    fn parse() {
+        super::parse(TEST_NAME)
+    }
+
+    /// Test that parsing and unparsing KCL produces the original KCL input.
+    #[tokio::test(flavor = "multi_thread")]
+    async fn unparse() {
+        super::unparse(TEST_NAME).await
+    }
+
+    /// Test that KCL is executed correctly.
+    #[tokio::test(flavor = "multi_thread")]
+    async fn kcl_test_execute() {
+        super::execute(TEST_NAME, true).await
+    }
+}