Inform user when GF API key used is wrong.
Inform user when GF API key used is wrong.

Fixes #1519
(fontbakery-metadata-vs-api is already wrapped in try/catch to bail out when the query can't be properly parsed.)

graphicore/fontbakery,graphicore/fontbakery,graphicore/fontbakery,googlefonts/fontbakery,moyogo/fontbakery,moyogo/fontbakery,googlefonts/fontbakery,googlefonts/fontbakery,moyogo/fontbakery