Configure Babel to target your current version of Node with Jest

[gziolo]

Description

It aims to fix the issue raised by @youknowriad in WordPress/wordpress-develop#69 (comment).

Fixes #16262.

@wordpress/babel-preset-default babel-jest and core-js dependencies are required to make sure we can use "import" and ESnext features while writing tests, I think this should be absorbed by @wordpress/scripts

This PR adds the missing babel-jest dependency and tries to update Babel config to remove the need for core-js but it seems like it's not working as intended.

How has this been tested?

Screenshots

Types of changes

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.

[youknowriad]

The changes seem reasonable to me. We'd have to try an update the setup in Core later to test this properly.

[gziolo]

The changes seem reasonable to me. We'd have to try an update the setup in Core later to test this properly.

Yes, I can take care of it as soon as this change is published to npm.

I also want to set up a very basic e2e test in https://github.com/WordPress/gutenberg-examples which would help to ensure this works as expected whenever we publish a new version to npm.