Add initial validators

[deads2k]

• [x] don't use bools
• [x] don't use maps
• [x] don't use floats
• [ ] don't use unsigned ints
• [x] no new fields can be required
• [x] don't remove fields
• [ ] don't change field types
• [ ] don't tighten validation rules
• [ ] don't loosen validation rules (warning)
• [x] status subresource must be used if status exists
• [ ] conditions must match metav1.Conditions with proper SSA tags
• [x] 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.