GenerateInteropFormCommandPackage should derive from AsyncPackage instead of Package #6
Description
Warnings:
(VSIXInteropFormsToolkit) The package (VSIXInteropFormsToolkit.GenerateInteropFormCommandPackage) class in any VSIX supporting Visual Studio 2015 or later should derive from AsyncPackage instead of Package. Read more about using AsyncPackage here: https://aka.ms/asyncpackage.