CLI: Remove babel-register in favor of esm

[ndelangen]

Issue: having babel-register to transpile our CLI code when starting is bad

What I did

I migrated it to use -r esm instead

[vercel]

This pull request is automatically deployed with Now.
To access deployments, click Details below or on the icon next to each push.

[ndelangen]

@Hypnosphi Could you submit your review for this possibly as soon as is convenient for you? We'd like to get this merged asap.

Thanks! ♥️

[shilman]

❤️

[Hypnosphi]

What is the lowest Node version that our CLI officially supports?

[Hypnosphi]

Before the change, it was 8: https://github.com/storybookjs/storybook/blob/next/lib/cli/.babelrc#L5

Maybe we should just transpile this package, as we do with other ones?

[shilman]

@Hypnosphi esm is compat with Node 6+ so i think this is a safe change.

[Hypnosphi]

@shilman but our own sources can use some newer features

[ndelangen]

@Hypnosphi We currently don't AFAIK,

I'm ok with someone changing it over to transpile everything instead.

[shilman]

@Hypnosphi open to doing that in a subsequent PR but want to get this out to address a core-js related issue in the CLI

[Hypnosphi]

is bad

Some additional context wouldn't hurt our future selves