cubicweb #1942655 cubes skeleton : add file encoding information (at least sometimes) [validation pending]

When you create a cube with -a option (author name) and the name contains a non ascii character, many files of the cube's skeleton need encoding information to become valid python files.

prioritynormal
typebug
done in3.14.4
load0.100
load left0.000
closed by#c04676b16c59 ([config] add file encoding information to python files (closes #1942655)