[FIX] Fix logging in adni to bids

[NicolasGensollen]

The function create_file in the adni-to-bids converter is executed in a multiprocessing context but doesn't handle the logging of messages in the sense that child processes do not configure their own logger.

This has a few consequences like the fact that messages logged from child processes aren't formatted or might even be missing.

This PR proposes a quick fix of re-configuring the clinica logger in child processes.

Ideally, we should have a process-safe logging architecture which would avoid race conditions (especially when logging to files for instance).
A classical solution is to dedicate a process to the logging task while other working processes send their logging messages through a Queue.

[AliceJoubert]

Thank you @NicolasGensollen !!
Messages of all levels from these files now appear properly in the terminal. That also means we get even more info messages than before and we might want to get rid of some of them later