Add direct ROS 2 CycloneDDS Subspace overlay

[dallison]

Summary

• Add ROS 2 overlay files and Subspace vendor package for CycloneDDS/RMW testing.
• Add direct CycloneDDS and rmw_cyclonedds patches that route local shared-memory delivery through Subspace.
• Extend the ROS2 performance matrix for Subspace/Iceoryx comparisons, fan-in/out scenarios, and memory reporting.

Test plan

• bazelisk test //c_client:client_test --config=macos_arm64 --test_output=errors
• python3 -m py_compile ros2/test/run_perf_matrix.py