Add mock modem service operations in Telephony

Bug: 205101043
Bug: 203241555
Test: manual
Change-Id: I65127fc43c62b52e3efaa99d06bf77855aab7bb0

telephony/java/com/android/internal/telephony/ITelephony.aidl

@@ -2513,4 +2513,14 @@ interface ITelephony {
 
     /** Check if telephony new data stack is enabled. */
     boolean isUsingNewDataStack();
+
+    /**
+     *  @return true if the modem service is set successfully, false otherwise.
+     */
+    boolean setModemService(in String serviceName);
+
+    /**
+     * @return the service name of the modem service which bind to.
+     */
+    String getModemService();
 }