Add a verbosity option

[n-peugnet]

There is a small problem with this option as we have 2 log levels:

• the log level of the LOGFILE logger (which is now debug)
• the log level of the STDOUT logger (which is now warn)

So I am not sure yet what would this option do. Also do we really want to keep the STDOUT logger ?

[n-peugnet]

For this, picocli (the module we use to parse cli args) has a cool feature: repeated boolean options which can be used to define the log level with the number of v

E.g.

command	console log level
ppi	warn
ppi -v	info
ppi -vv	debug
ppi -vvv	trace

[n-peugnet]

I think the verbosity option should be used only for the STDOUT appender and two more options should be added for the LOGFILE appender:

• --log-level: for the level of the log file (default: debug but should be changed to info in main and maybe keep debug on test)
• --log-file: the file to use for logging (default: target/ppi.log but should be changed to some OS dependent standard location)