4416 - show versions of installed packages

[batkot]

Took my chances on implementing @fendor suggestions from @lucalabs-de #4430 MR.

Inlay Hints

CodeLenses got hard to read when there are multiple packages in single line, so I added package name then to make it easier to understand.

As noticed in previous MR, because of limited positioning options lenses can look a bit wonky depending on cabal file formatting. Hover could be a nice (and easy to add) fallback as well, but I'm not sure about status of hover ticket (#4417) and for now I just decided to avoid unnecessary conflicts.

Closes #4416 (based on #4430)

[michaelpj]

Personally I'd be somewhat inclined to do this in a hover rather than an inlay hint, but debatable.

[michaelpj]

Not sure what a coherent argument would look like, but I would argue something like:

• Inlay hints are good for things you always want to see that provide missing context
• Inlay hints are often supposed to be something you can "accept", which adds the content into the buffer. But the inlay hint here isn't valid syntax!
• Hovers are good for extra information that you want when you are focussing your attention on a specific thing. I think I mostly want to know package versions when I'm thinking about a specific package dependency, so I think that suits hovers a bit more?