Changes to allow improved template logic when creating publishers and subscribers

[gonzodepedro]

This PR adds the functionality to allow the creation of publishers and subscribers using the Protobufe type, instead of a TypeAdapter type, which makes the code more readable.

The user would be able to use this:

publisher_ = this->create_publisher<std_msgs::msg::pb::String>();
subscription = this->create_subscription<std_msgs::msg::pb::String>()

Instead of the old way:

publisher_ = this->create_publisher<std_msgs::msg::typesupport_protobuf_cpp::StringTypeAdapter>()
subscription = this->create_subscription<std_msgs::msg::typesupport_protobuf_cpp::StringTypeAdapter>(

In order to allow for this, a call to the RCLCPP_USING_CUSTOM_TYPE_AS_ROS_MESSAGE_TYPE macro is generated for each of the generated protobuf types along with the required TypeAdapter.