Use a logger in the launcher thread and in the main thread to produce diagnostic messages

Use a logger (similar to the one in fireworks, see two examples [1]) for all messaging and to streamline the console output, especially warnings and errors of the launcher thread.

[1] https://git.scc.kit.edu/ce7802/vre-middleware/-/blob/master/engine/wfengine.py#L336, https://git.scc.kit.edu/ce7802/vre-middleware/-/blob/master/engine/wfengine.py#L346 [2] https://docs.python.org/3/library/logging.html