Referencing parts of other mock data

[mgrsskls]

The idea would be to have something like this when referencing other mock data:

$ref: /template-components/frontpage/header/menu/dropdown#/items

or when referencing the mock data of a variant:

$ref: /template-components/frontpage/header/menu/dropdown#variant-name/items

Another idea would be to create definitions:

$variants:
  - $name: foo
    items:
      $ref: #items

$defs:
  items: []