Provide a guidance/support for integration with Terranix (IoC)

[aleks-sidorenko]

Hi, we have good consistent opiniated structure for defining systems.
However if one want to integrate IoC tools like terraform (terranix) for managing infra - we don't have guidelines/support for that.
Should we have infra folder in the root of flake repo?
Should we have modules/terraform for reusable modules just like for nixos/darwin?

We probably need guidances and library support for that.