This is a mess. The version is AUR is still outdated and also doesn't
install anymore. Fedora 38 carries the latest version of it so use that
now. Keep the old steps in case we need to switch again in the future.
* SingleExecutor: added TODOs
* test `SingleExecutor` with files and project
* SingleExecutor: process markup files after code when scanning project
* TestSingleExecutor: generate scoped files before calling executor
* CI-unixish.yml: added `--output-on-failure` to CTest call
* helpers.cpp: improved error reporting in `~ScopedFile()`
* use unique filenames in executor tests to avoid collisions
* fixed `functionStatic` selfcheck warnings
Oliver Stöneberg
Daniel Marjamäki