VS extension: Add templates for Visual Basic

[Berrysoft]

It is able to write in Visual Basic with Avalonia now. It would be more easier if templates for Visual Basic were added.

[DualBrain]

Feel free to take a look at some VB templates for Avalonia UI that are available (as source) over at https://github.com/CommunityVB/Templates/tree/main/src/avalonia

Will eventually make these available as a nuget package; but they are available now in source and certainly could use some testing/feedback.

[Nukepayload2]

I've ported all the desktop templates to VB, including the source generator. I use it at work, and its stability has been valided for 7 months.

dotnet new install Nukepayload2.Templates.Avalonia