Better $ref support

[lornajane]

Not all the use cases work as I would expect when $ref is in the value to apply. For example the following overlay:

overlay: 1.0.0
info:
  title: Update stuff
  version: 1.0.0
actions:
- target: $.paths.*.get
  update:
    parameters:
      - $ref: "#/components/schemas/filterSchema"

Produces this for the first GET PathItem:

      parameters:
        - &ref_0
          $ref: '#/components/schemas/filterSchema'

And then for all the others:

      parameters:
        - *ref_0

Which isn't what I'd expect.

The $ref: line should be added to the document as-is, everywhere it applies. It's the responsibility of the user to make sure that reference actually exists.