Replace keystone-next prototype with keystone-next dev and a config option to determine if migrations should be used or not

[emmatown]

Currently, it's not very clear what people should use and what keystone-next prototype is and isn't compatible with, this PR makes it clear what command you should run and what commands you can't use if you're not using migrations. For example, we had an example that had dev and prototype scripts which doesn't make sense since they're mutually exclusive workflows. This replaces keystone-next prototype with a db.useMigrations option to determine if Keystone should use migrations or push the schema with the potential for data loss.

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[changeset-bot]

🦋 Changeset detected

Latest commit: 2726276

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 18 packages

Name	Type
@keystone-next/keystone	Major
@keystone-next/types	Major
@keystone-next/test-utils-legacy	Patch
@keystone-next/benchmarks-legacy	Patch
@keystone-next/example-auth	Patch
@keystone-next/app-basic	Patch
@keystone-next/example-ecommerce	Patch
keystone-next-app	Patch
@keystone-next/example-roles	Patch
@keystone-next/example-sandbox	Patch
@keystone-next/example-todo	Patch
@keystone-next/admin-ui	Patch
@keystone-next/auth	Major
@keystone-next/api-tests-legacy	Patch
@keystone-next/admin-ui-utils	Patch
@keystone-next/cloudinary	Patch
@keystone-next/fields-document	Patch
@keystone-next/fields	Patch

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[timleslie]

Looks good 👍