Support test and filter plugins

[felixfontein]

Also improves support for lookup plugins by handling the special option _terms.

Tests will fail at the moment.

Result:

• Filter plugins: https://ansible.fontein.de/collections/ansible/builtin/#filter-plugins
• Test plugins: https://ansible.fontein.de/collections/ansible/builtin/#test-plugins
• Lookup plugin example: https://ansible.fontein.de/collections/ansible/builtin/first_found_lookup.html#terms

[briantist]

Ah! I didn't realize this wasn't done/published yet. Explains why my docs are not showing it and by references are wrong 😅
ansible-collections/community.hashi_vault#263

Any guess on when this will be released (approximately)?

[felixfontein]

Let's discuss this at Tuesday's DaWGs meeting. (I.e. definitely not before then :) )

[felixfontein]

@briantist @samccann @acozine thanks for reviewing and commenting on the output :)