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/builtins/Array/array-shrink-during-find-crash.js

@@ -0,0 +1,25 @@
+load("test-common.js");
+
+try {
+    var a, callbackCalled;
+
+    callbackCalled = 0;
+    a = [1, 2, 3, 4, 5];
+    a.find(() => {
+        callbackCalled++;
+        a.pop();
+    });
+    assert(callbackCalled === 5);
+
+    callbackCalled = 0;
+    a = [1, 2, 3, 4, 5];
+    a.findIndex(() => {
+        callbackCalled++;
+        a.pop();
+    });
+    assert(callbackCalled === 5);
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}