Copy build_clazy_clang_tidy job from kdav's .gitlab-ci.yml and adapt for our use case.

2 jobs for !7 with fix-gitlabci in 49 minutes and 50 seconds (queued for 27 minutes and 46 seconds)
latest detached
Status Job ID Name Coverage
  Build
passed #63730
build_clazy_clang_tidy

00:29:45

passed #63729
linux kf5-qt5 qt5.12

00:20:05

53.0%