ipaserver: Modify vars loading in ansible-freeipa roles.

When loading variables in all ansible-freeipa roles, it is expected
that a file with these variables is present for each supported Linux
distribution, and then, based on the information about the distribution
provided by Ansible, the correct file is loaded.

Previously, only the facts `distribution` and dinstribution version
related facts were used, which required specific files, or links to
files for distributions in the same "family", which will probably have
the same variables set.

This change adds searching for files based on the `os_family` fact,
allowing distributions that follow the same family rules to be
supported, without any changes to the codebase. It is still possible
that a specific distribution configuration overrides the default
behavior, as `os_family` has lower priority than `distribution`.

For example, distributions on the `RedHat` family, like Oracle Linux,
Alma Linux, and Rocky Linux, work withoutadding new files, or links to
files, to fill the `vars`.

Fix issue #573. Fix issue #523.