Create a Nightwatch function to search elements by nested selectors

In Nightwatch 3.x we can do this using the nested calls of browser.element() like this:

        browser.click(
          this.api
            .element(pager.component)
            .findElement({ selector: pager.item, index: 0 }),
            .findElement({ selector: pager.actionButton }),
        )

And you can upgrade Nightwatch to 3.x even for Drupal 10, so seems it's the better way than re-implementing the wheel on the Test Helpers side.

murz → closed merge request !114