Create 4.x branch that uses Package Manager from core

+1 for getting this done for Drupal CMS launch.

I've manually tested it using the branch from this issue and all seems well (enough).

phenaproxima → credited tedbow → .

Crediting @pameeela for manual testing and @tedbow for out-of-band discussion about the tag.

Merged into 4.x.

Automatically closed - issue fixed for 2 weeks with no activity.