Make batch attestation keys/certs optional

Test: VtsKeyMintTargetTest
Bug: 329399923
Bug: 329269183
Change-Id: Iecb6623479fc18753cace6524be13815e89d435f
diff --git a/main.rs b/main.rs
index 8033f60..ee89dd7 100644
--- a/main.rs
+++ b/main.rs
@@ -92,7 +92,7 @@
     };
     let dev = kmr_ta::device::Implementation {
         keys: Box::new(TrustyKeys),
-        sign_info: Box::new(CertSignInfo),
+        sign_info: Some(Box::new(CertSignInfo)),
         attest_ids: Some(Box::new(AttestationIds)),
         sdd_mgr: Some(Box::new(shared_sdd_mgr)),
         bootloader: Box::new(kmr_ta::device::BootloaderDone),