Secretkeeper VTS: Use trait CborSerializable

With Request/Response packets impl CborSerializable. Use the methods
from those.

Test: atest libsecretkeeper_comm_nostd
Bug: 291228655
Change-Id: Ib0daf9c0aa3417befedbc130725fb3445b327079
diff --git a/security/secretkeeper/aidl/vts/Android.bp b/security/secretkeeper/aidl/vts/Android.bp
index fac16f6..93192e9 100644
--- a/security/secretkeeper/aidl/vts/Android.bp
+++ b/security/secretkeeper/aidl/vts/Android.bp
@@ -29,6 +29,7 @@
         "libsecretkeeper_comm_nostd",
         "android.hardware.security.secretkeeper-V1-rust",
         "libauthgraph_core",
+        "libcoset",
         "libauthgraph_vts_test",
         "libbinder_rs",
         "liblog_rust",