Add tutorials CI and documentation gallery

This MR answers :

• #101 (closed)
  • Add the nblink files
  • Update the tutorials index.rst
  • Update conf.py to specify thumbnails in the gallery
• #123 (closed)
  • Add tutorials in the CI
  • Add "aidge_learning" in the setup.sh to compile aidge_learning in the build:ubuntu_cpp
  • Update aidge_learning commit (where a dummy test have been added)