Plotting Widget Features

During inspections (and navigation) it can be helpful to see real-time plots of collected sensor data. The plotter widget should ideally include:

- [x] ability to live-plot data from the vehicle
- [x] MAVLink data
- [x] other data (e.g. CPU load, network latency)
- [ ] multi-signal plots
- [ ] multiple lines on one graph (e.g. two temperature readings)
- [ ] line styling, to help differentiate lines
- [ ] maybe support a "line dashes", where 0 = no line, 1 = full line, and higher numbers determine the number of dashes across the width of the plot (an exponential scale may help keep numbers reasonable)
- [ ] point styling, to help differentiate data sources, and allow scatter plots
- [ ] point symbols
- [ ] point size
- [ ] signal modifiers
- [ ] maths operations (e.g. `abs(roll)`, or `depth+altitude` for bathymetry)
- [ ] display-modifiers (e.g. scatter point colour and/or size based on a different signal, like depth coloured by heading)
- [ ] text annotations (e.g. title, axis labels, legend, colourmap descriptors)
- [ ] axis scales and modifiers (e.g. log time scale to squish together old data to not scroll past it as fast, constant offset)
- [x] axis limits settable to auto or fixed values
- [ ] option to choose between plotting variables against time or a different variable (like on an oscilloscope)

Some internal discussion [here](https://bluerobotics.slack.com/archives/C03FLG1LVUM/p1666856985461659)

The issue identifies the plotting widget and lists possible multi-signal, styling, modifier, annotation, and axis features, but names no files or tests. Start by locating the widget's current plotting implementation and choosing a narrowly scoped unchecked requirement. Done should include the selected behavior and validation that the resulting plots work as described.

Written by the indexing model from the issue text.