docs: Add first version of a script that can convert forms from core into tabbed restructured text pages

[Monviech]

I did quite a few of these so lets automate it.

The result can be seen in this PR:

#696

The script is executed like this inside the docs folder:

/bin/python3.11 ./collect_forms.py --input /src/git/core/src/opnsense/mvc/app/controllers/OPNsense/Firewall/forms

And it will generate the following output:

Generated: source/manual/forms/Firewall/categoryedit.rst
Generated: source/manual/forms/Firewall/dialogfilterrule.rst
Generated: source/manual/forms/Firewall/dialognptrule.rst
Generated: source/manual/forms/Firewall/dialogonetoonerule.rst
Generated: source/manual/forms/Firewall/dialogsnatrule.rst
Generated: source/manual/forms/Firewall/geoipsettings.rst
Generated: source/manual/forms/Firewall/groupedit.rst

This can be used as includes in a manual like this:

.. include:: /manual/forms/Firewall/dialogfilterrule.rst

Now we can regenerate this tabbed view we have used in the manual without manually editing it. Its just one script execution and thats it.