Hardcoded npmjs and Next Upgrade script fails with minimum age gates

[Noriller]

Goals

1. Being able to upgrade to something other than just the "latest" from npm.
2. Use .npmrc / registry values to check next versions and updates
3. registry should be configurable and not hardcoded to npmjs

Non-Goals

No response

Background

next.js/packages/next/src/server/dev/hot-reloader-shared-utils.ts

Line 17 in 02d8ff2

res = await fetch('https://registry.npmjs.org/-/package/next/dist-tags')

Next hardcodes from npm instead of using registry from .npmrc or from other config.

In my case, I catched that by using MSW catching all unhandled requests.

Then, it doesnt allow for npx next upgrade because of versions from proxy registry (verdaccio in my case).

Proposal

1. Let npmjs as fallback, but fetch from .npmrc (or similar) where the project is actually fetching next pkg
2. (and/or) upgrade script taking a version so we can use the script to upgrade, but choosing the version to upgrade. Also nice in the case of upgrading from an older version (in the future), since you could gradually upgrade instead of going straight to latest.