New servicedelegationtarget management module

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

    plugins/modules/ipaservicedelegationtarget.py

The servicedelegationtarget module allows to ensure presence and absence of
servicedelegationtargets and servicedelegationtarget members.

Here is the documentation of the module:

    README-servicedelegationtarget.md

New example playbooks have been added:

    playbooks/servicedelegationtarget/servicedelegationtarget-absent.yml
    playbooks/servicedelegationtarget/servicedelegationtarget-member-absent.yml
    playbooks/servicedelegationtarget/servicedelegationtarget-member-present.yml
    playbooks/servicedelegationtarget/servicedelegationtarget-present.yml

New tests for the module:

    tests/servicedelegationtarget/test_servicedelegationtarget.yml
    tests/servicedelegationtarget/test_servicedelegationtarget_client_context.yml
    tests/servicedelegationtarget/test_servicedelegationtarget_hostprincipal.yml