authfs: Integration test

This test currently only runs on Android, not VM, to verify existing
features. It needs to be moved into the VM when ready.

Bug: 178874539
Test: atest AuthFsHostTest

Change-Id: I7334b6ae0e684c36a9e350fe148c12a382ef076e
diff --git a/authfs/Android.bp b/authfs/Android.bp
index 4a20a0c..85f2abb 100644
--- a/authfs/Android.bp
+++ b/authfs/Android.bp
@@ -52,7 +52,13 @@
     name: "authfs_device_test_src_lib",
     defaults: ["authfs_defaults"],
     test_suites: ["device-tests"],
-    data: [
+    data: [":authfs_test_files"],
+}
+
+filegroup {
+    name: "authfs_test_files",
+    srcs: [
+        "testdata/cert.der",
         "testdata/input.4k",
         "testdata/input.4k.fsv_sig",
         "testdata/input.4k.merkle_dump",