pcd_to_pointcloud: add latch param using transient_local QoS

[remco-r]

I missed this feature from ROS1. Implemented using transient_local QoS. Tested in humble using: ros2 run pcl_ros pcd_to_pointcloud --ros-args -p file_name:=<file_path> -p latch:=true

Afterwards a single pointcloud was received with ros2 topic echo or in rviz, while these nodes were not active when the pointcloud was published.