Migrate: Remove database create logic inside lift, fail fast if the database doesn't exist.

[matthewmueller]

Right now lift has all sorts of logic to create a database. This won't work for every datasource and it'd be better to create datasouces in prisma init or the prisma studio flows, where we can ask the user some questions and hold their hand.

If the user doesn't use the prisma init flow, we'll expect them to bring their own database (BYOD).

Instead Lift commands will check if it can connect to the database and fail fast if it can't connect. This will resolve #26 and it will make the migration engine code cleaner.

Thoughts @schickling ?

[pimeys]

My rust code is here:

https://github.com/prisma/prisma-engine/pull/34

Next week working with @timsuchanek to use this in lift/photon.

[timsuchanek]

Shipped in latest alpha.