add option to choose prepend/append in merge

plugin/builtin/patchtransformer/PatchTransformer_test.go

@@ -321,13 +321,13 @@ spec:
         old-label: old-value
     spec:
       containers:
-      - image: nginx
-        name: nginx
       - args:
         - proxy
         - sidecar
         image: docker.io/istio/proxyv2
         name: istio-proxy
+      - image: nginx
+        name: nginx
 ---
 apiVersion: apps/v1
 kind: Deployment
@@ -747,10 +747,7 @@ spec:
         name: test-deployment
         ports:
         - containerPort: 8080
-          name: take-over-the-world
-          protocol: TCP
-        - containerPort: 8080
-          name: take-over-the-world
+          name: disappearing-act
           protocol: TCP
 `)
 }

plugin/builtin/patchtransformer/go.mod

@@ -4,9 +4,9 @@ go 1.14
 
 require (
 	github.com/evanphx/json-patch v4.5.0+incompatible
+	github.com/pkg/errors v0.8.1
 	sigs.k8s.io/kustomize/api v0.6.2
 	sigs.k8s.io/kustomize/kyaml v0.8.1
-	github.com/pkg/errors v0.8.1
 	sigs.k8s.io/yaml v1.2.0
 )