Add tracing instrumentation using tracetools

[christophebedard]

With this instrumentation, rmw_zenoh_cpp is supported out-of-the-box by tools that process ROS 2 trace data, such as Eclipse Trace Compass.

It's pretty straightforward except for a few things:

1. Getting the rmw_publisher_t * for the rmw_publish tracepoint
   • Add it to PublisherData.
2. Getting the source timestamp for the rmw_publish tracepoint
   • Getting the source timestamp of a message being published is needed for tracking messages from publisher to subscription.
   • Since Add timestamp to rmw_publish tracepoint ros2_tracing#74, we're getting the source timestamp for a published message from rmw. This means we don't need to instrument the underlying middleware itself, which we used to have to do.
   • I modified create_map_and_set_sequence_num() to be able to extract the source timestamp.
3. Getting the/a subscription rmw GID for the rmw_subscription_init tracepoint
   • See the comment before the tracepoint.

I'm open to suggestions.

[christophebedard]

Oh, looks like this repo aims to support Iron, Jazzy, and Rolling on the rolling branch. I will deal with that after a first round of review.

[christophebedard]

@Yadunund @clalancette any interest in having this?

[Yadunund]

@christophebedard we'd love to have this! We're sort of freezing the rolling branch at the moment to focus effortts on getting the #276 merged before we add new features. So let's wait for that to get in before merging this PR . By then Iron would have ben sunsetted so we won't have to worry about failing Iron CI job.