Update to use scram implementation from edgedb-js + polish login page design

[jaclarke]

Fixes #404

@scotttrinh @beerose Want to do a quick pass over the copy, or does it look ok?

[scotttrinh]

My only feedback would be to either be more emphatic about suggesting gel ui or give more reason why. As it is, it seems like just a passing comment.

[jaclarke]

Yeah, I wasn't sure about putting too much emphasis on that message, as it's just guessing based on the server url and meant to help users that somehow end up on the login page (you should never see this page if you're using gel ui), so it could be wrong if you're running the server in docker or something. Maybe just saying that would resolve the issue, so something like 'It looks like you're running Gel locally. If you created the instance using the Gel CLI, the easiest way to login is by running the gel ui command from your project directory'?

[jaclarke]