Loaned message tests

[nightduck]

Description

This provides unit tests for the tracepoints added in rmw_cyclonedds PR#556 and rmw_fastrtps PR#871, confirming that the rmw_take tracepoint is called even when using zero-copy

Fixes #240

Is this user-facing behavior change?

No

Did you use Generative AI?

Yes, the initial draft was written entirely in Cursor's agentic tool. Review and revisions were done with a human (except the _CYCLO_DDS_SHM_XML string, which was AI generated)

Additional Information

[nightduck]

I locally confirmed that this passes when built against the latest version of rmw_cyclonedds and rmw_fastrtps PR#871, and it fails when built against versions of rmw_cyclonedds and rmw_fastrtps from before these tracepoints were added:
rmw_cyclonedds: e7f44399fbadb474f0136370c232ed7eaf5be581
rmw_fastrtps: e5c8a84386fd9059f99ed6710ad4d7ac80f089b0

[christophebedard]

Pulls: #241
Gist: https://gist.githubusercontent.com/christophebedard/da8cd515281e71dc599c8b9a52e9add7/raw/dfc312de713dd967b3efd6ada33f92f258a077d7/ros2.repos
BUILD args: --packages-above-and-dependencies test_tracetools
TEST args: --packages-above test_tracetools
ROS Distro: rolling
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/19000

• Linux
• Linux-aarch64
• Linux-rhel
• Windows

[christophebedard]

@nightduck the new tests are failing on all Linux jobs. Can you take a look? Also, GitHub CI doesn't seem to like launching roudi.