[TESTS] Update tests and add test for generate_artifacts (#311) (#319)

* [tests] use tmp_path instead of deprecated tmpdir
* cover some error cases
* [test] test cli displays help if verb missing
* add some fixme in the code
* exclude setup.py from coverage reporting
* add high lever testing for generate_artifacts verb

Signed-off-by: Mikael Arguedas <mikael.arguedas@gmail.com>
(cherry picked from commit fb226616)

Co-authored-by: Mikael Arguedas <mikael.arguedas@gmail.com>