callbacks: Enable ARA

[ARA Records Ansible][0] is a web-based reporting tool for Ansible.  It
consists of a callback plugin that submits task/playbook results to an
HTTP API and a browser GUI to display them.

[0]: https://ara.recordsansible.org/

ansible.cfg

@@ -15,3 +15,7 @@ remote_tmp = /var/tmp
 
 [callback_ntfy]
 server = https://ntfy.pyrocufflink.blue
+
+[ara]
+api_client = http
+api_server = https://ara.ansible.pyrocufflink.blue

plugins/callback/ara_default.py

@@ -0,0 +1 @@
+from ara.plugins.callback.ara_default import *