Add clang-tidy CI test

[lucafedeli88]

This PR introduces a new CI test that runs clang-tidy on all the tests and demos of picsar_qed.
Included/excluded clang-tidy checks as well as check options can be found in .clang-tidy. For the moment, this configuration file is identical to what is used in WarpX.

The PR also fixes all the issues found with the new clang-tidy CI test. In order to fix some issues properly, now C++17 is used (up until now the library used C++14)

[EZoni]

Looks good to me, all CI checks seem successful, so it's probably ready to merge. I left only two minor notes related to inline comments that might have been copied from WarpX.

[ax3l]

Restarting CI because of old PR.
(CI was green, but the last run was 2 months old.)

[ax3l]

Thank you, that LGTM.

[ax3l]

@lucafedeli88 let me know if you like to tag a new 25.02 release at the end of the months again, so we can easily track and pull it into WarpX.