Create a singleton that generates an empty bp file

This singleton will be used to generate a bp file based on
make-based product config later.

Test: m and CI
Bug: 367418637
Change-Id: I98caea5419f1facd3fa9ca5c6389d16a7aa2ce5d

android/Android.bp

@@ -88,6 +88,7 @@ bootstrap_go_package {
         "prebuilt.go",
         "prebuilt_build_tool.go",
         "product_config.go",
+        "product_config_to_bp.go",
         "proto.go",
         "provider.go",
         "raw_files.go",

android/product_config.go

@@ -14,7 +14,9 @@
 
 package android
 
-import "github.com/google/blueprint/proptools"
+import (
+	"github.com/google/blueprint/proptools"
+)
 
 func init() {
 	ctx := InitRegistrationContext

android/product_config_to_bp.go

@@ -0,0 +1,35 @@
+// Copyright 2024 Google Inc. All rights reserved.
+//
+// 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.
+
+package android
+
+func init() {
+	ctx := InitRegistrationContext
+	ctx.RegisterParallelSingletonType("product_config_to_bp_singleton", productConfigToBpSingletonFactory)
+}
+
+type productConfigToBpSingleton struct{}
+
+func (s *productConfigToBpSingleton) GenerateBuildActions(ctx SingletonContext) {
+	// TODO: update content from make-based product config
+	var content string
+	generatedBp := PathForOutput(ctx, "soong_generated_product_config.bp")
+	WriteFileRule(ctx, generatedBp, content)
+	ctx.Phony("product_config_to_bp", generatedBp)
+}
+
+// productConfigToBpSingleton generates a bp file from make-based product config
+func productConfigToBpSingletonFactory() Singleton {
+	return &productConfigToBpSingleton{}
+}