to support reset content filtered topic with empty string.

remove constness for rmw_subscription because is_cft_supported might be updated

Signed-off-by: Chen Lihui <lihui.chen@sony.com>

rmw_cyclonedds_cpp/src/rmw_node.cpp

@@ -2370,6 +2370,7 @@ static rmw_subscription_t * create_subscription(
   memcpy(const_cast<char *>(rmw_subscription->topic_name), topic_name, strlen(topic_name) + 1);
   rmw_subscription->options = *subscription_options;
   rmw_subscription->can_loan_messages = false;
+  rmw_subscription->is_cft_supported = false;
 
   cleanup_subscription.cancel();
   cleanup_rmw_subscription.cancel();
@@ -2488,7 +2489,7 @@ extern "C" rmw_ret_t rmw_subscription_get_actual_qos(
 }
 
 extern "C" rmw_ret_t rmw_subscription_set_cft_expression_parameters(
-  const rmw_subscription_t * subscription,
+  rmw_subscription_t * subscription,
   const char * filter_expression,
   const rcutils_string_array_t * expression_parameters)
 {