New servicedelegationrule management module

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

    plugins/modules/ipaservicedelegationrule.py

The servicedelegationrule module allows to ensure presence and absence of
servicedelegationrules and servicedelegationrule members.

Here is the documentation of the module:

    README-servicedelegationrule.md

New example playbooks have been added:

    playbooks/servicedelegationrule/servicedelegationrule-absent.yml
    playbooks/servicedelegationrule/servicedelegationrule-principal-member-absent.yml
    playbooks/servicedelegationrule/servicedelegationrule-principal-member-present.yml
    playbooks/servicedelegationrule/servicedelegationrule-target-member-absent.yml
    playbooks/servicedelegationrule/servicedelegationrule-target-member-present.yml
    playbooks/servicedelegationrule/servicedelegationrule-present.yml

New tests for the module:

    tests/servicedelegationrule/test_servicedelegationrule.yml
    tests/servicedelegationrule/test_servicedelegationrule_client_context.yml
    tests/servicedelegationrule/test_servicedelegationrule_hostprincipal.yml