Put configured callbackSystem in quotation marks

[owi92]

I'm talking about the callbackSystem in the "Back to {callbackSystem}" button.

This seems unecessary when passing a name like "Tobira" or "Opencast", where you end up with a coherent sentence, but with names like "Videoportal Universität Bern (Tobira)", it might be a little clearer to delimit the name - that way it's super duper clear that we're not trying to build a gramatically correct sentence.

This was suggested in elan-ev/tobira#1232 (comment).

_{(If you are wondering why we don't just pass the quotation marks as part of the callbackSystem parameter in Tobira specifically: currently this uses the configured site title, and ideally this won't need a dedicated editor config section.)}

[LukasKalbertodt]

Alternatively, one could also use a slightly grey background and/or border around the {callbackSystem}.

[Arnei]

I'm slightly against enforcing quotations marks, those likely don't make sense in every language. Lukas idea might be better.