Inlay hint for package imports

[michaelpj]

Is your enhancement request related to a problem? Please describe.

When looking at an import, it's not obvious at a glance what package it comes from.

Describe the solution you'd like

There is a syntactically valid way to show what packages imports come from: PackageImports! So we can have inlay hints where inserting the inlay hints gives valid Haskell, which is quite nice.

Something like this:

import <hint>"base"</hint> Data.List

Describe alternatives you've considered

We already show packages and versions when hovering on imports, but this makes it even more immediate. It's probably going to be a bit of a love-it-or-hate it thing. And PackageImports is I think "discouraged" so maybe we shouldn't be encouraging people to use it.