Merge topic 'ctest-error-exit'

8dbb7f65f9 ctest: Exit 1 when argc == 1 and no input file exists
fa7c993ef9 Help: Document plain `ctest` command-line signature and exit code

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: scivision <michael@scivision.dev>
Merge-request: !11743