CoverPage: Don't use StyleWithNonce for cli interactions

[yhabteab]

Before:

PHP Fatal error:  Uncaught Error: Call to undefined method Icinga\Application\Cli::getRequest() in /icingaweb2/library/Icinga/Web/Window.php:114
Stack trace:
#0 /icingaweb2/library/Icinga/Util/Csp.php(90): Icinga\Web\Window::getInstance()
#1 /icingaweb2/library/Icinga/Util/Csp.php(78): Icinga\Util\Csp::getInstance()
#2 /usr/local/src/ipl-web/src/Compat/StyleWithNonce.php(19): Icinga\Util\Csp::getStyleNonce()
#3 /usr/local/src/ipl-web/src/Style.php(105): ipl\Web\Compat\StyleWithNonce->getNonce()

[nilmerg]

I'd rather make StyleWithNonce not using a nonce while not in Web context. What do you think?

[yhabteab]

I'd rather make StyleWithNonce not using a nonce while not in Web context. What do you think?

That would be even better, but I didn't want to add checks like isWeb() in ipl-web.

[nilmerg]

StyleWithNonce is a compat class, where such checks are legitimate.