Allow synchronous action for some TestNG tests

NullPointerEexceptions occur specifically in TestNG execution because one thread has finished and nulled out various fields before another test line acts on a result (calcMan null in AlignCalcWorker, for instance, or mapping is null in StriuctureMapper).

This branch allows TestNG tests to run on Bob's computer without spawning unnecessary threads or using SwingUtilities.invokeLater.

Clearly it does not fully test Jalview's multithreading. What it does is optionally test functionality without resulting in unidentified failures simply due to the test not waiting long enough for an asynchronous process to complete.

Also could be useful in headless environments.