Lower ROS benchmarks' storage requirements

[hidmic]

Feature description

We currently bag all topics for ROS 1 and ROS 2 benchmarks. This makes it easy to post-process both input and output data, at the expense of huge storage requirements.

It'd be best to record only what's new (and necessary, as per user specification) and transparently yield the same input + output view to the user when accessing benchmark results.

Implementation considerations

Restricting the recording is easy (just forward a set of topics), offering a unified view is the tricky part. Hard links to input bags and synchronizing bag reads may be a path forward.