Support to import ROS 2 data (MCAP) #480

Let s allow user to bring ROS 2 bags instead LAZ/CSV.
MCAP has C++ API, and ROS 2 CDR is easy to write with TDD and agentic coding.

Idea:

• open ROS 2 BAG
• choose topics and fields (little like in cloud compare)
• load data to step 1 (or convert to LAZ/CSV)