LibJS: Reorganize tests into subfolders

Author: https://github.com/mattco98
Commit: 4c48c9d69d
Pull-request: https://github.com/SerenityOS/serenity/pull/2681
Reviewed-by: https://github.com/linusg

Libraries/LibJS/Tests/operators/delete-global-variable.js

@@ -0,0 +1,16 @@
+load("test-common.js");
+
+try {
+    a = 1;
+    assert(delete a === true);
+
+    assertThrowsError(() => {
+        a;
+    }, {
+        error: ReferenceError
+    });
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}