Compress and convert sensor_msgs::msg::PointCloud2 to rclcpp::SerializedMessage

[alireza-moayyedi]

Hi,

As I mentioned in #55, I want to compress and publish my sensor_msgs::msg::PointCloud2 directly in my code to avoid the middle man topic converter node. So I took a look at the topic converter's code and tried to do something similar here. This way, in my own code I can have something like this:

Initialization:
..............
#include "cloudini_ros/conversion_utils.hpp"

// Cloudini compression publisher
const std::string compressed_topic_type = "point_cloud_interfaces/msg/CompressedPointCloud2";
cloudini_publisher_ =
  this->create_generic_publisher("~/points/compressed", compressed_topic_type, qos_pub);
.............

When required:
.............
if (cloudini_publisher_->get_subscription_count() > 0) {
  cloudini_publisher_->publish(Cloudini::ConvertToCompressedCloud(pcd_msg, resolution));
}

To be frank I do not have the full scope of Cloudini so I am not sure if this is the cleanest or easiset way to do this. In any case, I got what I was looking for!

By the way the commit is on top of #55 so you can just review the .cpp and .hpp files here and ignore the Cmake and package.xml ones. As as soon as #55 is merged I will rebase. Sorry for being impatient!