Support reading $ref: #/paths/*

[AbhimanyuG]

Currently APISprout has strict behavior where it expects $ref to be pointing to components/schemas only. However standard resolver tools like Speccy resolves paths to something like these:

field:
  $ref: '#/paths/inventory~get~blahblah/get/responses/200/content/application~1json/schema/items/**'

As per OpenAPI standards as well above behavior is allowed, although not ideal.

So instead of failing, $refs should be read/crawled regardless of where they point.

[AbhimanyuG]

@danielgtaylor Just found out you already reported this issue in kin-openapi: getkin/kin-openapi#24

[AbhimanyuG]

Duplicate of #1