Gating tests: use loginctl, dump env
    
    - instead of hacky mkdir /run/user/<fedora id>,
      use loginctl enable-linger and hope that it
      has the same effect.
    
      reason: the mkdir doesn't seem to be 100% effective.
      There are cases in which the first rootless podman
      invocation fails with:
    
        Error: could not get runtime: cannot mkdir /run/user/1000/libpod: mkdir /run/user/1000/libpod: no such file or directory
    
    - for future spelunking, dump environment at start
      of each test (both root and rootless). Suggested
      by Giuseppe.
    
    Signed-off-by: Ed Santiago <santiago@redhat.com>