colin checks if pkg_mgr calls clean all

[phracek]

This check means, that after package installation
yum/dnf clean all is called.

We have to go through layers and find whether dnf/yum install foobar and dnf/yum clean all is called in the same layer.
Input for check is an image.
Output of the check is True, whether dnf clean all is called in the same layer
and False in opposite case.

[TomasTomecek]

+1

It's possible that we might get some false positives. Worst case we can tune/disable the check in some rulesets.