Add topic statistics helper plot

[carlossvg]

This PR adds a script to plot metrics from the topic statistics topic.

• Test script with all the options

Instructions

1. Enable enable_topic_stats: True param

2. Launch demo

 ros2 launch pendulum_bringup pendulum_bringup.launch.py

3. Log controller_stats in csv format

ros2 topic echo /controller_stats --csv > controller_stats.csv

4. Run script passing the csv file:

python3 topic_statistics_plot.py path/to/controller_stats.csv --show -m message_period

5. Check plot

python3 topic_statistics_plot.py path/to/controller_stats.csv --show -m message_age

Notes

• Apparently the topic statistics maximum and minimum are not calculated for the measurement window but for the whole time. This makes the plot less informative.
• The script assumes the order of the metrics is fixed. This could change in the future. This can be improved by using the data_types information.
• The script will fail if there are NaN.

[LanderU]

Some minor python style suggestions added.

[LanderU]

LGTM!