Add clang-format target by default in KDEFrameworkCompilerSettings
This MR revisits the idea of adding the target by default in the frameworks compiler settings.
The .gitignore files have been taken care of and @kossebau has removed (ab)uses of this module in non-framework projects.
Of course this will wait for 5.79 being tagged.
When we mass reformat the projects we can deactivate formatting in directories like templates.