Add Check Option to Format CLI Command

Problem

Currently, one can only format a schema using prisma format but can’t validate the schema is formatted, in CI for example.

Suggested solution

Add a --check option to the CLI for validating the schema is properly formatted.

Alternatives

Add integration with Prettier which already has this functionality as described here: https://github.com/prisma/prisma/issues/1761

Additional context

In https://github.com/amplication/amplication we are currently struggling with keeping consistent formatting of our Prisma Schema file. I can write a script to validate it in our CI but I think this functionality is relevant for more users and would be much simpler to implement if it was part of the CLI.

[iddan]

In prettier I have a command to validate the code is formatted correctly: prettier --check (https://prettier.io/docs/en/cli.html#--check). I thought it would make sense that prisma format will have a way to validate the schema is formatted correctly and if not it will return status code 1 (so it can fail CI)

[janpio]

Still do not fully get it. Do you want a command that tells you true/false if a schema is already formatted or not? Or something else?