Add a backend option for the computation of deformation cone

[jplab]

This is a quick follow-up on #39496 that adds a deformation cone method that encodes regular subdivisions.

With this option, we may speed-up the computations

📝 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

#39496

[fchapoton]

    poly = Polyhedron(ieqs=ieqs, backend)
                                        ^
SyntaxError: positional argument follows keyword argument

[fchapoton]

attention, comme je t'avais dit, j'ai fait des modifs directement sur ta branche sur github sur l'autre ticket. Il aurait fallu tirer ces modifs avant de batir d'autres commits par dessus ta branche. A priori, ca va merger sans probleme, mais on ne sait jamais.