Use fsverity metadata file for authfs

Instead of alternative signature and merkle tree, authfs will use
.fsv_meta files, which are installed to the system partition with
PRODUCT_SYSTEM_FSVERITY_GENERATE_METADATA Makefile.

Bug: 205987437
Test: atest ComposHostTestCases AuthFsTestCase
Test: run "atest ." inside authfs/tests
Change-Id: Ia9db78663e0e322c7a59305c67ac5b84716d8efe
diff --git a/authfs/src/fsverity/metadata/Android.bp b/authfs/src/fsverity/metadata/Android.bp
new file mode 100644
index 0000000..39ce515
--- /dev/null
+++ b/authfs/src/fsverity/metadata/Android.bp
@@ -0,0 +1,20 @@
+rust_bindgen {
+    name: "libauthfs_fsverity_metadata_bindgen",
+    wrapper_src: "metadata.hpp",
+    crate_name: "authfs_fsverity_metadata_bindgen",
+    source_stem: "metadata_bindings",
+    apex_available: ["com.android.virt"],
+}
+
+rust_library {
+    name: "libauthfs_fsverity_metadata",
+    crate_name: "authfs_fsverity_metadata",
+    srcs: [
+        "metadata.rs",
+    ],
+    rustlibs: [
+        "libauthfs_fsverity_metadata_bindgen",
+    ],
+    edition: "2018",
+    apex_available: ["com.android.virt"],
+}