Add attestation certificate generation and identity credential tags.

Bug: 149908474
Test: atest android.security.identity.cts.AttestationTest
Test: atest VtsHalIdentityCredentialTargetTest
Test: atest android.hardware.identity-support-lib-test

Change-Id: I18c5d05d806d4157c9dce42a398cc89421e26907
diff --git a/identity/aidl/default/WritableIdentityCredential.h b/identity/aidl/default/WritableIdentityCredential.h
index b380f89..b182862 100644
--- a/identity/aidl/default/WritableIdentityCredential.h
+++ b/identity/aidl/default/WritableIdentityCredential.h
@@ -64,10 +64,13 @@
     string docType_;
     bool testCredential_;
 
-    // These are set in initialize().
+    // This is set in initialize().
     vector<uint8_t> storageKey_;
+
+    // These are set in getAttestationCertificate().
     vector<uint8_t> credentialPrivKey_;
     vector<uint8_t> credentialPubKey_;
+    vector<vector<uint8_t>> certificateChain_;
 
     // These fields are initialized during startPersonalization()
     size_t numAccessControlProfileRemaining_;