Add napari plugin debugger launch instructions to the plugin debug guide

[seankmartin]

📚 New content request

While https://napari.org/dev/plugins/debug_plugins.html exists, and has some nice information - it may be missing some prerequisite steps such as how launch a debugger from IDE (e.g. VSCode) that contains a running napari window. Also how to inspect the code from there.

Outline

There is a potential that this could be solved by a simple screen recording of having a plugin in VSCode, and then running a launch script in the debugger like:

import napari

viewer = napari.Viewer()
viewer.window.add_plugin_dock_widget("napari-plugin-name")
napari.run()

And setting a breakpoint or raising an exception to show the output.
I don't know how regular video format is in the current docs, so open to exploring this!

Further context

This arose from a discussion around debugging napari plugins from the recent napari community meeting at euro time. I'm open to thoughts on how to achieve this @psobolewskiPhD, @Czaki

[psobolewskiPhD]

Love this.
I mean your screen share was 🤯 for me, but most of the text of the OP basically explains it. So could go with text & code, plus a screen shot or a video.
Worth also looking for a link to some info about python debugging.