Allow to user to input custom (floating) versions through the PM UI for solution level

[erdembayar]

NuGet Product Used

Visual Studio Package Management UI

Repro Steps & Context

Previously we implemented this feature at project level PMUI, this is for solution level.

Change version input to a Combo Box displaying available version depending on the user input. This will allow users to select a floating version to install.

Fyi @martinrrm

[jeffkl]

Team Triage: @erdembayar and @martinrrm please give this a cost estimate and add to the project if we're going to work on this or add it to icebox.