Added VSToolsManifest so controls will show up in the toolbox

[dotMorten]

Addresses #1464

[Odonno]

@dotMorten How do you set the icon for each control in the toolbox?

[dotMorten]

@Odonno I'm currently not, but there's a few ways to do it as described here: https://docs.microsoft.com/en-us/nuget/guides/create-uwp-controls

We can create a follow-up issues to add icons. The odd thing is though... a couple of the controls somehow gets icons. No idea where those came from, but I'm thinking it's a bug since it looks like it might be pulling them from WPF icons where the name matches.

[nmetulev]

Tested, works as expected

[dnfclas]

@dotMorten, thanks for signing the contribution license agreement. We will now validate the agreement and then the pull request.

Thanks, .NET Foundation Pull Request Bot