Tests for capture workflow

Capturing can trigger re-focusing and therefore needs to take care of refocusing if problems occur. This change creates test cases to verify that capture and focus interact properly.

Since capture count test cases overlap with this test set, functionality from the capture count test cases are extracted to TestEkosCaptureHelper.

Fixed problems

• A meridian flip that is executed while re-focusing leads to the situation that after a completed meridian flip, guiding and capturing do not restart
• Scheduler ignores jobs with durations < 1sec (detected when refactoring capture count test cases)
• Crash when refocusing when FITS viewer is disabled
• Focusing is aborted when capture aborts

Open problems

• When a meridian flip aborts focusing, the focuser remains at that position where it was when the meridian flip started and does not move to the last focus position. This is not optimal, but fixing it is surprisingly complex. The risk creating a regression is significantly higher than the benefit. Therefore, this will be issue of a separate merge request.