Add initial validators

[deads2k]

• don't use bools
• don't use maps
• don't use floats
• don't use unsigned ints
• no new fields can be required
• don't remove fields
• don't change field types
• don't tighten validation rules
• don't loosen validation rules (warning)
• status subresource must be used if status exists
• conditions must match metav1.Conditions with proper SSA tags
• all lists must have SSA tags
• no durations (for kube, openshift configuration API allowed)
• enumerated values should use CamelCase
• optional should be pointers (for kube, openshift configuration API allowed)
• defaulted values have to be optional to pass CR validation
• stable versions cannot coexist with unstable versions
• booleans cannot be defaulted
• no uses of corev1.ObjectReference
• no uses of corev1.LocalObjectReference
• no new enumerated values (warning)
• no removed enumerated values (error)
• no replace in list (warning)

[pgodowski]

I see the list is a combination of strict rules and some are more like guidances, like enumerated values should use CamelCase - I don't see why would this matter, for the CRD compatibility?

[openshift-bot]

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/lifecycle stale

[deads2k]

/lifecycle frozen

still working through.