WebUI tests: Extend netgroup tests with more scenarios
    
    Extended webui group automation test with below scenarios
    Scenarios
     *add netgroup with invalid names
     *add and delete records in various scenarios
     *verify button's action in various scenarios.
    
    https://pagure.io/freeipa/issue/7505
    
    Signed-off-by: Varun Mylaraiah <mvarun@redhat.com>
    Reviewed-By: Petr Vobornik <pvoborni@redhat.com>
    Reviewed-By: Michal Reznik <mreznik@redhat.com>