Create visualizer for system_error_monitor

[h-ohta]

Checklist

• I've read the contribution guidelines.
• I've searched other issues and no duplicate issues were found.
• I've agreed with the maintainers that I can plan this task.

Description

The diagnostics_aggregator is visualized in rqt_robot_monitor, and DiagnosticsArray messages are also visualized in rqt_runtime_monitor.

However, we don't have any visualizer for system_error_monitor now.
For example, when we fall into emergency, we have to echo some topics from system_error_monitor with terminal and analyse them to resolve.

Purpose

The purpose of this task is to create some visualization ways to check system_error_monitor status with GUI more easily.
I believe this function can able to make our developers to resolve the problem like emergency more quickly.

Possible approaches

Various approaches are considered

• create rqt plugin same as rqt_robot_monitor
• create rviz plugin
• create other GUI approaches

Definition of done

• created some visualization ways
• We can check the status and the problem by using them

[kenji-miyake]

@h-ohta Have you tried ros2 run rqt_runtime_monitor rqt_runtime_monitor --ros-args -r /diagnostics:=/diagnostics_err?

[h-ohta]

Yes, I tried it.
I confirmed when a diag are staled, the [Single Point Fault] flag is added to it.
However, I can't confirm emergency and emergency_holding status from it.

[stale]

This pull request has been automatically marked as stale because it has not had recent activity.