Please add support for Visual Basic.Net

### System information

- **OS version/distro**:
- **.NET Version (eg., dotnet --info)**:

### Issue
It looks like this Visual Studio extension does not currently work in Visual Basic .Net projects.

- **What did you do?**
Installed the ML.Net Model Builder extension in Visual Studio 2019.
Created a new VB.Net project and a new C# project.

- **What happened?**
The ML.Net Model Builder extension worked in the C# project (Add - Machine Learning opened the ML.Net Model Builder tab). Pass for C#.

The ML.Net Model Builder extension did not work in the VB.Net project (Add - Machine Learning was not even available). FAIL for VB.Net.

- **What did you expect?**
It would be nice for this extension to work in VB.Net projects as well.
You would more than double your audience!

### Source code / logs

Please paste or attach the code or logs or traces that would be helpful to diagnose the issue you are reporting.