DotUninstall, a cross platform UI version of this tool

I built a minimalist UI for this tool using Uno a few weeks ago, and after a few iterations it is now mature enough to be announced here for more audience.

It relies on the same detection/uninstall logic from this repo (inherited via submodule), but also enriches the display by pulling down .NET metadata from `builds.dotnet.microsoft.com`. Through quick links to release notes, support policies, etc., developers can get a better understanding of what bits they installed.

[Feedback is welcome](https://github.com/lextudio/DotUninstall/issues).