openqa etc: reinstall local Python libs when Python ver changes
    
    In openqa/dispatcher, relvalconsumer and check-compose roles, we
    install Python libraries from git checkouts (these are things we
    don't really want to package as they change too much). This
    enhances those roles so that we check whether pip considers the
    libraries to be installed, and install them if it doesn't. The
    purpose is to catch when the Python version rolls over on system
    upgrade, and reinstall the libraries in that case - I got bitten
    by this when upgrading to F32, I forgot to reinstall these libs
    for Python 3.8, and it broke things for a couple of days before
    I noticed and fixed it manually...
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>