New layout for retired packages
    
    Fixes fail during execution operation over the already retired
    package or module.
    Test `is_retired` is run in the beginning, but the method was not
    reachable when the package was already retired - no layout was
    selected in this case and it left `self.layout` unset. A new layout
    was created.
    
    Also modifies related tests. When a package is retired, a directory
    contains only a marker and other tracked files are removed from git.
    There should not be any difference between retired DistGit or SRPM
    layouts.
    
    JIRA: RHELCMP-1967
    Resolves: rhbz#1867822
    
    Signed-off-by: Ondrej Nosek <onosek@redhat.com>