LibJS: Skip iterator result object allocation in for..of and for..in

Introduce special instruction for `for..of` and `for..in` loop that
skips `{ value, done }` result object allocation if iterator is builtin
(array, map, set, string). This reduces GC pressure significantly and
avoids extracting the `value` and `done` properties.

This change makes this micro benchmark 48% faster on my computer:
```js
const arr = new Array(10_000_000);
let counter = 0;
for (let _ of arr) {
    counter++;
}
```

Libraries/LibJS/Bytecode/Instruction.h

@@ -51,6 +51,7 @@
     O(EnterObjectEnvironment)          \
     O(EnterUnwindContext)              \
     O(Exp)                             \
+    O(ForOfNext)                       \
     O(GetById)                         \
     O(GetByIdWithThis)                 \
     O(GetByValue)                      \