[ROS 2] Usability issues with plotting for ported ROS 1 tutorial

[wjwwood]

While going over the use of rqt_plot in this ROS 1 tutorial (https://wiki.ros.org/ROS/Tutorials/UnderstandingTopics#Using_rqt_plot) in preparation for porting it to ROS 2, we noticed some usability issues:

• It is not possible to adjust the width of the rolling window, which makes it hard to see patterns in the waveform for this tutorial.

• The plotting always includes the 0 on the y-axis, rather than dynamically setting both the y-axis bounds, which causes the data to be quashed to the top of the plot.

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See how it is in ROS 1:

Versus in ROS 2 as of Dashing: