Display license status in management console
Created by: attfarhan
Fixes https://github.com/sourcegraph/sourcegraph/issues/1432.
As discussed in the issue, there is a lot of copy-pasta. Primarily from the license code from enterprise/cmd/frontend/licensing/
into the new enterprise management console binary, and several components from web/src/enterprise
to display the product subscription. Please leave comments if any questions. I would recommend actually running this locally to test too.