Setup clang-tidy

As discussed in aidge#155, it would be nice to setup clang tidy for this project. This can be done in multiple steps :

• Defining the clang-tidy options we need, writing the file and adding it to the project. At this point, it will be ready to use by editors with clangd LSP.
• Enabling clang-tidy in CMake
• Enabling clang-tidy in the CI

Documentation for clang-tidy-18 : https://releases.llvm.org/18.1.0/tools/clang/tools/extra/docs/ReleaseNotes.html, in particular all clang-tidy checks

Note: A different clang-tidy for unit_tests/ should probably be used.