This commits introduces changes to test number 4, so it must keep
more than one PKG. Also, it introduces a 5th test to verify that the
<remove_all/> functionality does delete everything in the depot.
Issue genodelabs#4866
This commits introduces improvements to the test functions to avoid
code duplication, and renames these functions to reflect better what they
are used for.
Issue genodelabs#4866
The depot_remove component can delete PKG archives with
automatically resolving dependencies and deleting archives that are not
required on the system anymore.
Issue genodelabs#4866