authfs: run unit tests in presubmit

Test: TH
Bug: 178874539
Change-Id: If4df4177dcc426a79d2ff4a4ab90510abdddc7d5
diff --git a/authfs/TEST_MAPPING b/authfs/TEST_MAPPING
new file mode 100644
index 0000000..d0c0b09
--- /dev/null
+++ b/authfs/TEST_MAPPING
@@ -0,0 +1,7 @@
+{
+  "presubmit": [
+    {
+      "name": "authfs_device_test_src_lib"
+    }
+  ]
+}