Show a usage hint for CustomScriptPlugin in configuration UI
When a formatter tool referenced in CustomScriptPlugin
's style cannot be
found (not installed), error messages are easy to miss. They are written
not into systemd journal, but into ~/.xsession-errors, because the error
occurs in the shell rather than in KDevelop directly.
The usage hint that emphasizes the external tool executable dependency of each custom script style should reduce usage mistakes and wrong assumptions by users.