Replace openapi Fake with kube-openapi version

There are two version of this fake class, let's just use that one
version.

vendor/k8s.io/kube-openapi/pkg/util/proto/openapi.go

@@ -59,7 +59,7 @@ type SchemaVisitor interface {
 }
 
 // SchemaVisitorArbitrary is an additional visitor interface which handles
-// arbitrary types. For backwards compatability, it's a separate interface
+// arbitrary types. For backwards compatibility, it's a separate interface
 // which is checked for at runtime.
 type SchemaVisitorArbitrary interface {
 	SchemaVisitor