Small refractoring of generating automatic documentation

[maxradx]

For developers

Currently, the documentation can be automatically generated using 2 scripts

1. python scrip combine_dot_files.py (to generate a class diagram), under the src folder
2. generate_documentation in the SlicerCART folder (generate and build html documentation)

It would be more convenient to merge the number 1 (need to be ran first if no diagram priorly setted) in 2, and move the global script in the root folder (instead of SlicerCART.py)

[SomeoneInParticular]

I already kind of worked on this while fixing the Github website CI fix; in fact, that made the second script obsolete!

Will look into folding the second script into it soon, just prioritizing a refactor which will (hopefully) fix the QT import bug. See PR #223