Provide `norpa` and `rpa` option on startup

[Arvengeance]

If we have test cases and tasks on execution path, Robot won't start up, even when we only execute either tests or tasks.

We currently must provide robot with the --rpa or --norpa option until https://github.com/robotframework/robotframework/issues/4360 is fixed.

This issue is closed, when you can provide the option to webservice.

[Noordsestern]

Similar to #16 , could be solved by allowing argumentfiles.