Line Plot Widget for sequential data

Hi @dstansby , hi all,

I currently have a couple local implementations of a plotter with line plots based on metadata.
Data are stored in metadata because sometimes I generate data from intensity images which in napari, as far as I know, do not have 'properties' or 'features'.
I would like to have a general line plotter to import from. Thus, I naturally thought about napari-matplotlib!

To encompass all layer types, including the Image layer, I thought about storing the plotting data as a nested dictionary in the layer metadata, somtehing like:

{'plugin_name': 
    {'x_data': array},
    {'y_data': array},
    {'other_data': array} }`

I have some code that works with that kind of structure. Would that be an interesting contribution here?
From a plugin developer's perspective, storing data as a two level dictionary would allow filtering data origin (by 'plugin_name', so different plugins could fit) apart from regular image metadata and then axes would come from the internal keys. @kevinyamauchi , do you think such structure would be interesting?

Here is an example:

For example, for plotting a time series, a developer could include a time dimension array there as well.

If this should not belong here, that's also OK, I could place it somewhere else, just let me know ;)
I can make a Draft PR to further discuss this.

Best,
Marcelo

No files, tests, or entry points are identified. First clarify the proposed metadata structure and widget scope with maintainers; done would be an agreed implementation plan for plotting sequential data across the relevant napari layer types.