Proposal: port StdVectorPythonVisitor from Pinocchio's bindings

[ManifoldFR]

The header is here: https://github.com/stack-of-tasks/pinocchio/blob/devel/bindings/python/utils/std-vector.hpp (or a more recent version).
I recently suggested moving/copying the StdVectorPythonVisitor template from Pinocchio's bindings upstream to this repo, so that downstream packages don't have to import or copy the header from Pinocchio.

We could also import the StdContainerFromPythonList template.

What do we think of this ? I could do it if we choose to go ahead with it.

[jcarpent]

Please move forward ;)

[jcarpent]

Thanks in advance

[jcarpent]

Solved via #325.