ARQGRA-266: bug with jquery locators and waitings fixed

Thr problem was the following scenario:

1. an action reloading page started performing,
2. waiting started,
3. JQuery page extension installed,
4. page reloaded (all page installed page extensions dropped),
5. page extension mechanism tried to check whether the JQuery extension
   is instaled -> FAIL

The solution of this scenario is to use @JavaScript interfaces instead of
raw page extensions. The @JavaScript interfaces can handle this interleaving
since ARQGRA-262.