Fixes from my notes of the last day of March 2024 session

See merge request !120

Fixes from my notes of the first day of March 2024 session

See merge request !117

Introduce maybe_unused.

Closes #137

See merge request !115

Very few corrections noted in day 3

See merge request !119

Concept should anyway be more developed!

Rephrase differently the naming of parameters argument - why same name could be used in two different scopes.

Use CppyyKernel to run the notebooks instead of Xeus-cling.

Closes #101

See merge request !114

#101 Installation: no need to clone the cppyy_kernel repo and then invoke pip: pip may be invoked directly.

#101 Binder: copy the content of the folder from https://gitlab.inria.fr/sgilles/clang-tidy-feedback project which works with exact same dependency.

- The one related to Xeus cling is no longer useful as Xeus cling is dismissed.
- There is no need to provide a dedicated cppyy_kernel one for the training session: the basic
Docker image built for CppyyKernel project is good enough.

Reactivate properly the CI, minus the jobs no longer required to build aforementioned
Docker images.