KEP-2887: Enum Types for OpenAPI (kubernetes#2888)

* [PRR] KEP-2887 Enum Type for OpenAPI

* KEP-2887: OpenAPI Enum Types

* annotation -> marker

* reword value auto-detection.

* kube-builder syntax compatibility.

* re-target to OpenAPI v2.

* field pruning for disabling this feature.

* goal: unify with kubebuilder.

* Update keps/sig-api-machinery/2887-openapi-enum-types/README.md

Co-authored-by: Daniel Smith <[email protected]>

* rewrite non-goals.

* Update keps/sig-api-machinery/2887-openapi-enum-types/README.md

Co-authored-by: Daniel Smith <[email protected]>

* reword enum field pruning.

* preprocessor for these don't want enums.

* update TOC.

* Update keps/sig-api-machinery/2887-openapi-enum-types/README.md

Co-authored-by: Daniel Smith <[email protected]>

* polish assumptions on impl.

* Update keps/sig-api-machinery/2887-openapi-enum-types/README.md

Co-authored-by: Daniel Smith <[email protected]>

* reword non-goal

* allow client open enum.

* omit the enum linter.

may add it back later.

* update TOC.

Co-authored-by: Daniel Smith <[email protected]>

keps/prod-readiness/sig-api-machinery/2887.yaml

@@ -0,0 +1,3 @@
+kep-number: 2887
+alpha:
+  approver: "@deads2k"