`seeNumberOfElements()` doesn't count <input>s with Bootstrap's `.custom-control-input` class

Next problem with [Bootstrap custom radio button](https://getbootstrap.com/docs/4.5/components/forms/#radios) after https://github.com/Codeception/module-webdriver/issues/21

`seeNumberOfElements()` doesn't count those radiobuttons:
```html

```
This is probably because of `z-index:-1` in Bootstrap's CSS:
```css
.custom-control-input{position:absolute;left:0;z-index:-1;width:1rem;height:1.22rem;opacity:0}
```
Background: When using Bootstrap's *custom* radiobuttons, the standard browser widget is replaced by some other widget (SVG?) for nicer graphics.

I'm filing this here mainly to see if somebody else encounters it. A possible solution could be to set a configuration parameter in `acceptance.suite.yml` to switch the concerned methods' behavior to be compatible with Bootstrap.

In my case I can't look at the page's source code (what I'm guessing that e.g. [`seeNumberOfElementsInDOM()`](https://codeception.com/docs/modules/WebDriver#seeNumberOfElementsInDOM) is doing), since I'm showing/hiding some radiobuttons with JavaScript, and I need to assert their *visibility.* My workaround: Count the *labels* instead:
```php
$I->seeNumberOfElements(['css' => 'div#foobar label'], 7);
```