New DNSConfig management module

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

plugins/modules/ipadnsconfig.py

The dnsconfig module allows to modify global DNS configuration.

Here is the documentation for the module:

README-dnsconfig.md

New example playbooks have been added:

playbooks/dnsconfig/set_configuration.yml
playbooks/dnsconfig/disable-global-forwarders.yml
playbooks/dnsconfig/disallow-reverse-sync.yml

New tests for the module:

tests/dnsconfig/test_dnsconfig.yml