Use OpenAPI when merging (3way) resources

- When merging (3way) resources use the patch strategy from the openAPI if the definition exists for the field
- Allow disabling of guessing patch strategy merge keys when no definition exists
- Support defining strategy and key directly on configuration fields through line and header coments
- Support attaching schema to parent fields of lists, and propagating -- e.g. that a field is a PodTemplate

kyaml/yaml/walk/visitor.go

@@ -4,6 +4,7 @@
 package walk
 
 import (
+	"sigs.k8s.io/kustomize/kyaml/openapi"
 	"sigs.k8s.io/kustomize/kyaml/yaml"
 )
 
@@ -16,11 +17,11 @@ const (
 
 // Visitor is invoked by walk with source and destination node pairs
 type Visitor interface {
-	VisitMap(nodes Sources) (*yaml.RNode, error)
+	VisitMap(Sources, *openapi.ResourceSchema) (*yaml.RNode, error)
 
-	VisitScalar(nodes Sources) (*yaml.RNode, error)
+	VisitScalar(Sources, *openapi.ResourceSchema) (*yaml.RNode, error)
 
-	VisitList(nodes Sources, kind ListKind) (*yaml.RNode, error)
+	VisitList(Sources, *openapi.ResourceSchema, ListKind) (*yaml.RNode, error)
 }
 
 // ClearNode is returned if GrepFilter should do nothing after calling Set