[Introspection] Better `introspect` success message

A successful introspect run currently looks like this:

λ npx prisma2@alpha introspect
Introspecting …
Done with introspection in 1.42s
Wrote schema.prisma

We should probably try to make this a bit nicer.

1. The text itself can be a lot more descriptive (“datamodel was added to your schema.prisma”) and for example offer next steps (“Now use prisma2 generate to create a Prisma Client for your database”).
2. We could also output some statistics about the datamodel that was added: x models, y relations, z indexes (Actually only the “model” part might be reasonably simple, but maybe this is a good place to go a bit overbord and have fun)

[janpio]

Then I suggest this iteration:

✔ Introspected 17 models and wrote them into prisma/schema.prisma in 1.36s

It changes the checkmark to a green one as suggested by @sorenbs, adds the number of models as suggested by @do4gr and outputs the actual path of schema.prisma.

If we agree on that I would persist it in https://github.com/prisma/specs/tree/master/cli#introspect so it can be implemented.

[sorenbs]

I would love to have statistics as suggested in 2.

We should also think about how to display failures / guard rails. Something like: 2 models and 7 relations were disabled because we couldn’t support them.

I don’t think we should print “next steps” as suggested in 1. It’s too much clutter.

I think it would be nice to add a green checkmark ala firebase:

Whatever we decide, the result should be a pr to the CLI spec.