Add framework boot image

Currently, it is just a placeholder that retrieves information about
the framework boot image from the dex_bootjars singleton.

Bug: 177892522
Test: m droid
Change-Id: Icd7943a37378a56c416e502aa29d6088c2f247d2
Exempt-From-Owner-Approval: https://crbug.com/gerrit/14008

boot/Android.bp

@@ -0,0 +1,18 @@
+// Copyright (C) 2021 The Android Open Source Project
+//
+// 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.
+
+boot_image {
+    name: "framework-boot-image",
+    image_name: "boot",
+}