NATT Keepalive RIL Implementation

RIL support for startKeepalive and stopKeepalive

Bug: 63942305
Test: vts
Change-Id: Ie4ad70b0120d234fc976a9e24e244c8bd9b08bfb
diff --git a/libril/ril_commands.h b/libril/ril_commands.h
index de73936..94c2a26 100644
--- a/libril/ril_commands.h
+++ b/libril/ril_commands.h
@@ -158,3 +158,5 @@
     {RIL_REQUEST_SET_CARRIER_INFO_IMSI_ENCRYPTION, radio::setCarrierInfoForImsiEncryptionResponse},
     {RIL_REQUEST_START_NETWORK_SCAN, radio::startNetworkScanResponse},
     {RIL_REQUEST_STOP_NETWORK_SCAN, radio::stopNetworkScanResponse},
+    {RIL_REQUEST_START_KEEPALIVE, radio::startKeepaliveResponse},
+    {RIL_REQUEST_STOP_KEEPALIVE, radio::stopKeepaliveResponse},