fix(PL-660): validate crd schemas against file content not deserialized representation

[davidmdm]

Not too long ago, schemas were added to represent the Joy CRDs. However the original implementation was wrong in that it would validate against the already serialized Go struct instead of the files root yaml node.

This would cause information loss and things to not get picked up by the schema validation.

For example with this change the internal tests started failing because versionKey which is an unknown property was being caught and it previously was not.

loading catalog: validating releases:
  - podinfo/demo: validation: error: #release.spec.versionKey: field not allowed
  - podinfo/dev: validation: error: #release.spec.versionKey: field not allowed
  - podinfo/platform: validation: error: #release.spec.versionKey: field not allowed
  - podinfo/qa: validation: error: #release.spec.versionKey: field not allowed

This has since been fixed in this commit.