b29db07c3b3d8937f53684fdbba985fec525d69d by Christian Heimes
Replace custom file_exists() and dir_exists() functions with proper
functions from Python's stdlib.
The change also gets rid of pylint's invalid bad-python3-import error,
https://github.com/PyCQA/pylint/issues/1565
With ansible 2.3.1 it is possible to have one place as an additional utils
module to do all the needed steps to be able to generate the environment for
new and older ipa versions.
The library modules are now a lot smaller.
The minimal ansible version has been increased to 2.3.1.
In the future it might now also be possible to have a special
ansible_ipa_client version for ipa < 4.4 in this utils module.
For ipa versions prior to 4.5 it is needed to use ipa-client-install script
as a source for functions. But the script contains a global finally clause
in which the generated ccache file gets removed. Threfore the script is
temporarily copied to ipa_client_install.py and the global finally clause
gets removed from the copy. All this is done in a temporary directory, which
gets removed right after the import has been done.
