Add new pref maxCodeHints

For #9529.
I confirmed this is a performance boost for Code Hints.
The following only works for positive integers, right?

```js
        if (Math.floor(value) !== value) {
            return false;
        }
```

`maxCodeHints` will always be positive, but this validation code needs to also handle negative integers as the code was already doing:

```js
        if (value > 0 && Math.floor(value) !== value) {
            return false;
        } else if (value < 0 && Math.ceil(value) !== value) {
            return false;
        }
```