galaxy.yml: Drop empty dependencies

Ansible 2.11 does not like to have empty dependencies. It will fail to
install the collection with "'NoneType' object has no attribute 'items'"
error. The empty dependencies have been removed.

The requirements for ansible in requirements.txt have been removed also.

Fixes #571 (error installing freeipa-ansible_freeipa-0.3.6.tar.gz)

ipabackup: Use module to get IPA_BACKUP_DIR from ipaplatform

Up to now a python snippet was used to get IPA_BACKUP_DIR from ipaplatform
but this was not working when ansible_facts was false due to not getting
ansible_python_interpreter set.

The module version is also working if gather_facts is turned off.

more minor documentation fixes, in vault module

ci: Run Github linter verification workflow in different jobs.

This patch modify Github 'lint' workflow to execute each linter
verifications as a separate job. This will allow us to easily see
which linter has failed, and ensure that all are executed, even
if one fails.

group: Reduce addition and deletion of members to changed only

hostgroup: Reduce addition and deletion of members to changed only

Add automember module

Fix and enhance tests

    There is a new automember management module placed in the plugins folder:

        plugins/modules/ipaautomember.py

    The automember module allows to ensure presence or absence of automember rules
    and manage automember rule conditions.

    Here is the documentation for the module:

        README-automember.md

    New example playbooks have been added:

        playbooks/automember/automember-group-absent.yml
        playbooks/automember/automember-group-present.yml
        playbooks/automember/automember-hostgroup-absent.yml
        playbooks/automember/automember-hostgroup-present.yml
        playbooks/automember/automember-hostgroup-rule-absent.yml
        playbooks/automember/automember-hostgroup-rule-present.yml

    New tests for the module:

        tests/automember/test_automember.yml

The task "Verify if modification worked" failed with PR #545 because the
ipaadmin_password was missing in the task.

Test task was missing zone and entry name.

Creation of reverse zone names were not using the pre-computed array,
and creation of the 8-bit network was wrong.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For the "Duplicate names in users failure test" failed_when: not
result.failed has been added as this test needs to fail.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

Fixed also "User test cert members present again" task, it was failing
due to also having first and last parameters with action: member.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

Only renamed again may not use failed_when result.failed as the rename
can not be idempotent.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.

For failed_when result.failed should be used to make sure that
the task fails if there was an error.