Use mcap convert ... without a ROS 2 installation

[Gomzinator]

I wanted to use mcap cli tool as a fully standalone tool to convert rosbag 2 from sqlite3 storage to mcap storage and be totally free from having to install ROS 2 installation simply to do ros2 bag convert in my pipeline.

I initialy thougth that it would guess how to ser/deser messages (or somehow read metadata info from the sqlite storage) but it failed with messages saying schema was not found.

Then I found issues like this comment from vj2181
who tried using --ament-prefix-path but failed.
Closest opened issue would be : #376
I couldn't find a discussion directly related to what I want to achieve.

Currently, I found this solution for myself and I'm happy with that but wanted to share my findings and maybe integrate a better solution directly in mcap cli : https://github.com/Gomzinator/mcap/releases/tag/0.0.59