Give new users option to explore Sourcegraph Cloud during installation

Created by: poojaj-tech

Installation results show a huge drop-off at login screen, and another drop-off point when asked to add repositories. Capture and encourage Sourcegraph usage by directing them to Sourcegraph cloud! https://docs.google.com/document/d/1vx4veLKDM5p3VSzxIVnCKkt2fTHmwusfHYabCWWmbUU/edit#heading=h.l6y86qxbnm0l