__package_pip: updating real detection of extras

As the previous detection took the wrong values, this explorer now
checks if packages for an extra are installed or not. If not, the extra
is not installed.

Based on the information of the explorer, it will install the package
again with the absent extras.
3 jobs for feature/__package_pip/extras in 1 minute and 7 seconds (queued for 8 seconds)
Status Job ID Name Coverage
  Test
passed #7857
pycodestyle

00:00:21

failed #7856
shellcheck

00:00:22

passed #7858
unit_tests

00:00:23

 
Name Stage Failure
failed
shellcheck Test
Removing cdist/util/__pycache__/
Removing cdist/version.py

Skipping Git submodules setup
Authenticating with credentials from job payload (GitLab Registry)
$ ./bin/cdist-build-helper version
$ ./bin/cdist-build-helper shellcheck
cdist/conf/type/__package_pip/explorer/extras:37:24: note: Useless cat. Consider 'cmd < file | ..' or 'cmd file | ..' instead. [SC2002]
ERROR: Job failed: exit code 1