Add fsverity_digests proto and metadata for APK

fsverity_digests will be used as a mapping file from files to their
fsverity digest, under system/etc/security/fsverity/BuildManifest.apk

Bug: 193113311
Test: build with PRODUCT_SYSTEM_FSVERITY_GENERATE_METADATA := true
Change-Id: I35da5e3bdbfc82e7baf5dc1c3f8ddf5fed951373
diff --git a/fsverity/Android.bp b/fsverity/Android.bp
new file mode 100644
index 0000000..b1d8965
--- /dev/null
+++ b/fsverity/Android.bp
@@ -0,0 +1,34 @@
+// 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.
+
+python_library_host {
+    name: "fsverity_digests_proto_python",
+    srcs: [
+        "fsverity_digests.proto",
+    ],
+    required: [
+        "fsverity",
+    ],
+    proto: {
+        canonical_path_from_root: false,
+    },
+    version: {
+        py2: {
+            enabled: true,
+        },
+        py3: {
+            enabled: true,
+        },
+    },
+}