v2: Handle relative references in OpenApiSchemaReference type

[captainsafia]

The OpenApiSchemaReference type included in this package provides support for resolving schema references to the top-level components.schemas object. The object doesn't play nice if the reference is a relative reference to a property in a recursive schema.

The serializer seems to detect these relative references correctly and serialize the correct references. It would be great if these resolutions also worked in the object model, particularly for users taking advantage of consuming APIs' in ASP.NET Core like OpenAPI schema transformers.

For example, given the following type hierarchy:

public class A
{
	public B B { get; }
}

public class B
{
	public C C { get; }
}

public class C
{
	public B B { get; set; } 
}

And the following schema:

{
  "type": [
    "object",
    "null"
  ],
  "properties": {
    "b": {
      "type": [
        "object",
        "null"
      ],
      "properties": {
        "c": {
          "type": [
            "object",
            "null"
          ],
          "properties": {
            "b": {
              "$ref": "#/properties/b"
            }
          }
        }
      }
    }
  }
}

#/properties/b should map to the properties.b schema when interacting with the OpenApiSchemaReference object for the schema.

[baywet]

While working on the proxy design pattern fix, I came to the same conclusion!
#2111 (comment)

The good news is that with the work I've done, it should now be a single place fix + providing a recursion method to resolve the actual schema when necessary.