* Remove Subsystems map and replace with RegisterSubSystem
* Clean up the logger
* Fix LOGFLAGS and make LongFile work correctly
* Parallelize the logger backend
* More logger cleanup
* Initialize and close the logger backend wherever it's needed
* Move the location where the backend is closed, also print the log if it panics while writing
* Add TestMain to reachability manager tests to preserve the same log level
* Fix review comments
Co-authored-by: Svarog <feanorr@gmail.com>
