Update to 2.14.4, bump astroid dep, fix and re-enable tests
    
    This switches to using github tarballs so we have the test suite,
    backports several patches from upstream, adds one slightly hacky
    fix for something upstream will hopefully fix better, and tweaks
    the test execution. With this the test suite passes fully with
    latest astroid and Python 3.11.
    
    I removed the clever-clever 'meta-pylint' test; there's no point
    running it and ignoring the result (as we do), and if you fix it
    to run properly it fails and I don't really want to dig into
    fixing it. I don't think it's our responsibility to make sure
    pylint gives itself a perfect score, that's not something that
    should pointlessly break our package builds. That's something
    upstream can care about if it wants to. Running the actual test
    suite is enough to tell us if something downstream is making
    pylint not work properly, which is what we ought to care about.