Autocomplete on `using` for uninstalled packages

[aplavin]

With the introduction of packages auto-installation a few julia versions ago, I noticed that I barely ever use ]add nowadays – only for package dev, sometimes. Mostly, I do using SomePackage, and Julia conveniently suggests to install this package for me.

The only issue in this workflow is a complete loss of package name autocomplete: using XXX<tab> doesn't suggest uninstalled packages from registries. Could this feature be added, at least when there are only a couple of possible matches?
For an existing example – Pluto does this.