RT log messages passing from RT to non-RT

We investigated, how log messages are currently passed from the RT thread to non-RT parts of the unit.

• Beginning with ControlThreadOutputBuffer
  • This seems to be a SPSC queue, implemented as ring buffer (own implementation, non-standard 🤢)
  • Unclear: how are sensor data and control targets written to buffer?
  • Found out, how messages are added
• ControlThreadOutputBuffer::addMessageToLog(...) is used to write messages into an RtMessageLogBuffer via macros

/cc @weiner