Draft: Work/ahq/add appium tests
This PR adds GUI tests to Okular.
It is based on this script https://invent.kde.org/teams/eco/feep/-/blob/master/usage_scenarios/okular/sus-okular_ucb.md
The PR is still in draft because it seems there is a bug in selenium-webdriver-at-spi on the function "find_elements" that throws an error where it shouldn't.