LibJS: Move tests to /Tests/LibJS

Author: https://github.com/gmta
Commit: https://github.com/LadybirdBrowser/ladybird/commit/e3faa9b5add
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/7572
Reviewed-by: https://github.com/trflynn89 ✅

Tests/LibJS/Runtime/loops/for-basic.js

@@ -0,0 +1,15 @@
+test("basic functionality", () => {
+    let a = [];
+    for (let i = 0; i < 3; ++i) {
+        a.push(i);
+    }
+    expect(a).toEqual([0, 1, 2]);
+});
+
+test("only condition", () => {
+    let a = [];
+    for (; a.length < 3; ) {
+        a.push("x");
+    }
+    expect(a).toEqual(["x", "x", "x"]);
+});