prosodyctl: Further deprecate start/stop/restart commands when installed Despite the warning we introduced, many people continue to try using prosodyctl to manage Prosody in the presence of systemctl (e.g. #1688). Also, despite the warning, prosodyctl proceeded with the operation. This means the commands could be invoked by accident, and cause a situation that is hard to recover from (needing to manually track down stray processes). This commit disables all the problematic commands by default, but this can still be overridden using --force or via a config option. We only perform this check when we believe Prosody has been "installed" for system-wide use (i.e. running it from a source directory is still supported).