godoc typename alignment

[grokspawn]

Action items from first review:

• godoc typenames aligning with json directives
• kubebuilder +optional and json omitempty alignment on optional fields

Additional items discovered and resolved in scope:

• types indicated as optional but traversed through pointers unconditionally
  • ClusterCatalog.Spec
  • CatalogSource.Image
  • ResolvedCatalogSource.Image