Properly generate $ref types on nodes, interfaces

[willosborne]

Feature Request

Description of Problem:

Currently the generator can generate arrays, strings, integers, consts properly. But if you have a schema with a $ref to a type, it just outputs {{ REF_[ key name ] }} and doesn't recursively instantiate.

For example, generating an interface that is based on the rate-limit-interface defined here. The usage example is the following. Note that only the interfaces are shown for brevity:

{
    "$ref": "https://raw.githubusercontent.com/finos/architecture-as-code/main/calm/draft/2024-04/meta/interface.json#/defs/rate-limit-interface",
    "type": "object",
    "properties": {
        "unique-id": {
            "const": "rate-limit-info"
        }
    }
}

{
          "unique-id": "unique-id-here",
          "key": "{{ REF_KEY }}",
          "time": -1,
          "time-unit": "{{ REF_TIME_UNIT }}",
          "calls": -1
 }

You can see key is a flat string that contains none of the structure of the real definititon.
What this should look like is:

{
    "key": {
        "rate-limit-key": "{{ RATE_LIMIT_KEY }}"
    }
}

This is really confusing because it implies it's just a single field, not an object - and obscures optional/additional fields.

Potential Solutions:

We can already do this recursive instantiation for metadata objects.
A relatively simple solution would be to unify the instantiation code to all use the generic/recursive system which would then bring these benefits to nodes and relationships.
Note that we would still need to keep the node/relationship-specific logic and merge the final objects together.

[willosborne]

This is done as of #521