adding method tikz to class Graph

[seblabbe]

Currently, we can create a TikzPicture from a graph as follows, but is raises an experimental feature warning:

sage: from sage.misc.latex_standalone import TikzPicture
sage: g = graphs.PetersenGraph()
sage: t = TikzPicture.from_graph(g)
<ipython-input-20-c4b6306d5e76>:1: FutureWarning: This class/method/function is marked as experimental. It, its functionality or its interface might change without a formal deprecation.
See https://github.com/sagemath/sage/issues/20343 for details.
  t = TikzPicture.from_graph(g)
sage: t

It was declared experimental during the review of #20343 because it should rather be a method of the class Graph.

This is what we do in this PR: we add a tikz method to the class Graph.

📝 Checklist

• The title is concise and informative.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation
• and checked the documentation preview.

⌛ Dependencies

None

Screenshots

As a consequence, the following now works in Jupyter. By default, it uses the dot2tex format if dot2tex is available:

[github-actions]

Documentation preview for this PR (built with commit 2a5b4d7; changes) is ready! 🎉
This preview will update shortly after each push to this PR.

[dcoudert]

I tested it and it is a nice addition.

[dcoudert]

This is much better and the examples are very nice (on my laptop).

[dcoudert]

default is None, not []. The same for other parameters.

[seblabbe]

None gets replaced by []. This is why I write that the default is []. I don't set the default argument to the empty list due to the gotcha related to doing this (https://docs.python-guide.org/writing/gotchas/).

If you insist that I replace [] by None and that I add a sentence after saying that None gets replaced by [], then I can.

[fchapoton]

the linter is not happy, please fix the offending line

[dcoudert]

LGTM.

[seblabbe]

Si j'ai ajouté Xavier comme reviewer, c'était pas pour mettre de la pression. C'est que j'étais dans son bureau et qu'il était curieux de tester aussi. Dans tous les cas, merci pour la relecture!

[dcoudert]

Pas de souci, et il ne faut pas qu'il hésite à revenir en arrière si il trouve qu'un truc ne va pas.

[xcaruso]

Non, tout va bien, c'est parfait.