Add a clazy -Werror CI
Clazy README at https://github.com/KDE/clazy/blob/1.4/README.md
Most of the checks are Qt related, but some are still valid for regular C++ like rule-of-two-soft, function-args-by-ref/value
Enables levels 0, 1 and 2, along with some manual ones
Disables non-pod-global-static, StructElement would need some rework to fix it and it's only a bit about optimization of start time, we can live with it
Not sure how we feel about using -Werror on this one :D