test: Check that the graph contains expected nodes

[wentasah]

I merged the main branch to graphs so that we can add tests for the graphing functionality. In this PR, I added the first simple test for the extract subcommand. Currently, this test fails (and has always failed) for rolling because the trace is empty. It needs to be investigated why (I can do it later).

However, the add_two_ints service test, which passes on the main branch fails on the graphs branch. So this is either caused by my incorrect resolution of a conflict between main and graphs branches, or it is caused by the "graphing" changes in this branch. @Pavel-Sedlacek can you look at that?

For completeness, the r2ta output is:

   [WARN  Ros2TraceAnalyzer::analyses::analysis::dependency_graph] Skipping edge PublicationInCallback: target ROS-node mapping missing for Publisher(ArcMutWrapper(Mutex { data: Publisher { rmw_handle: Known(832340992), rcl_handle: Unknown, rclcpp_handle: Unknown, rmw_gid: Known(Gid("010fbb2f8821b3bd00000000-00000103")), topic_name: Unknown, node: Unknown, queue_depth: Unknown, removed: false }, poisoned: false, .. }))
   The application panicked (crashed).
   Message:  no entry found for key
   Location: src/analyses/analysis/dependency_graph.rs:667

[Pavel-Sedlacek]

OK I found the issue, not sure where it originated but: The edge IDs (in fn process_edge) are assigned after the checks whether a node is part of a ROS node or not. If this check fails, the IDs are never assigned but are later (when the edge latencies are exported) expected to be present. You can merge this into graphs I will fix it there afterwards.