Fix/x kubernetes preserve unknown fields

[jknutson]

creating copy of pr kro-run#325 for the purposes of running the ci, test actions on my repo.

handle missing type in schema when x-kubernetes-preserve-unknown-fields is present

error message (formatted for legibility):

failed to build resource \"helmRelease\": 
  failed to generate dummy CR for resource helmRelease:
    error generating field spec: error generating field values:
      schema type is empty and has no properties