Warn if non-latest version is installed after explicit up

[fonsp]

This is just a draft PR to get the ball rolling to fix #1655. This only warns that a more recent version is available, it does not say why (I don't know how to implement that: #2583).

Demo

(Pkg) pkg> activate --temp
  Activating new project at `/var/folders/v_/fhpj9jn151d4p9c2fdw2gv780000gn/T/jl_9ciGWf`

(jl_9ciGWf) pkg> add Pluto@0.16.4 Configurations

# This installs [email protected] because of a bound by this old version of Pluto. 0.17 is available.

(jl_9ciGWf) pkg> up Configurations

    Updating registry at `~/.julia/registries/General.toml`
  No Changes to `/private/var/folders/v_/fhpj9jn151d4p9c2fdw2gv780000gn/T/jl_WblATC/Project.toml`
  No Changes to `/private/var/folders/v_/fhpj9jn151d4p9c2fdw2gv780000gn/T/jl_WblATC/Manifest.toml`

┌ Warning: Configurations (at 0.16.6) could not be updated to the latest version (0.17.0). Run `Pkg.add(name="Configurations", version=v"0.17.0")` to learn why.
└ @ Pkg.Operations ~/Documents/PkgClone.jl/src/Operations.jl:1309

[KristofferC]

The --outdated flag to status shows this information already:

What could be added is a small note very similar to the download icon that gets added when a package is not installed:

There could be a similar icon added to packages that are not on the latest version with a "hook" towards the --outdated flag to status for more information.

[IanButterworth]

@fonsp check out #2906, I think it might address the issue, in combination with the --outdated flag.
I'd be interested to see what you make of it

[IanButterworth]

I think #2906 covers this now