fix: Add license header to generated BYOB proto spec

Bug: b/357877119
Change-Id: Icc511e1886b9e813803646297bef318762731cf6
GitOrigin-RevId: 8ba3bee503bb73940f9aeb034bb6dd9c2efeca33

src/roma/tools/api_plugin/tmpl/byob/app/udf_interface.proto.tmpl

@@ -1,6 +1,16 @@
-// This file is @generated by src/roma/tools/api_plugin/tmpl/byob/app/md_cpp_client_sdk.tmpl. Do not edit.
-// Version: {{getVersion}}
-// Code Generator: {{getRomaGenerator}}
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
 
 {{- range $file := .Files}}
 {{- $file_name := .Name }}