Add admonition to gallery examples that require additional packages

[TimMonko]

References and relevant issues

Similar reasoning as #1021. When doing drag and drop from the gallery and now that examples are growing in their complexity and dependencies, it's important for us to warn users that they may not have all the dependencies to run the example. It's especially important now that we feature homepage examples that do not have typical napari dependencies

Built on #1021 (and #1026). two-dot diff https://github.com/TimMonko/docs/compare/gallery-links..TimMonko:docs:gallery-deps

Description

This adds an admonition if examples require dependencies not in "typical" napari installs (bundle, napari[all]). It identifies the missing dependencie(s) adds to the instructions, and links to other resources to install.

This uses mostly llm generated logic to compare napari[gallery] dependencies against napari[all] dependencies. It requires extra logic because we build against a remote, so we can't just special case anything in napari[gallery].

Note that pooch is not a direct dependency of napari (it comes from skimage[data] for the sample data), I had to special case ignore it.

Updated PR:

Original PR look:

[DragaDoncila]

Discussed at docs meeting, we think this might still be confusing for users because the "plugin installation guide" doesn't really talk about additional/other non-plugin packages, so it may not be clear that you can install them the same way as plugins.

Let's add a short section to the bottom of the finding-and-installing-plugins guide that says how you can install additional packages via the plugin manager (even if it's a bit redundant with the plugins bit). Then link to that from here.

[psobolewskiPhD]

Yeah, linking the plugin install guide feels off.
I think we'd want a page in the plugin manager docs on using the plugin installer to install arbitrary packages?

[TimMonko]

I made napari/napari-plugin-manager#213 to address this and point the link now to that resource

[psobolewskiPhD]

I noted this in the other PR too, but I really think this should be below the description.
I dislike how this distracts from the actual example!

Maybe the proper order is:
title
description
image
link buttons
code
?

[Czaki]

I remove it form milestone. If you gen into conclusion, it might still get into release

[TimMonko]

Moved it below description like in #1021, and updated the admonition to address the comments. Hopefully this is favorable now! I would really like to see this in 0.7.1 :)

[psobolewskiPhD]

The screenshot posted above looks a lot better to me.
Thanks!
I also approved the napari-plugin-manager PR.