* verbosity is raised to DEBUG to have more information in the logs
* color codes are now skipped in the `qltest.log` file
* they are still printed out on the console when running with
`--show-extractor-output`.
For the moment this removes the possibility to set custom flags or env
variables for the extractor via comments, but that can be added back
easily if needed with a different mechanism (like an `env` file).
This makes the clap flags overlay over `Config` entirely derived via an
attribute macro. Also, the `--intputs-file` option is replaced by a more
standard and versatile `@` parameter file mechanism.
