Load Ouster lidar raw data (lidar_packets) from ROS2 bagfile

[Grisly00]

When using a Ouster lidar with ROS, in some use cases it makes sense to record raw lidar packets instead of the standard Pointcloud2 messages as this saves computational resources and disk space while recording.
To work with the data it is currently necessary to replay the ROS bagfile and record the converted messages, which is cumbersome and error prone.

Therefore it would be a great feature to load the lidar packets directly into pointcloudset. In principle, this should be possible with the Python Ouster SDK.

For a discussion on the topic and a starting point to write a possible implementation see: ouster-lidar/ouster-sdk#524