Replace "edX Studio" with "{studio_name}"

For [OPEN-423](https://openedx.atlassian.net/browse/OPEN-423). This probably needs further discussion and review -- do we want to have a `{studio_name}` for "edX Studio" and a `{studio_short_name}` for "Studio"? Seems like several places use "Studio" rather than "edX Studio" rather intentionally.
I did it like this so that the translators didn't have to think about HTML. Can you suggest another way to do this that still makes thing easier for the translators?