ML.NET Model Builder creating muliple targets

[fswitz]

System Information (please complete the following information):
-- Model Builder Version: 16.0.1909.2101
--Visual Studio Version : 2019 16.3.2

Describe the bug
When adding the Machine Learning projects to a solution, different versions of frameworks/targets are created.

Project: WpfApp6 Target Framework .NET Framework 4.7.2
Project: WpfApp6ML.ConsoleApp Target Framework Net Core 2.1
Project: WpfApp6ML.Model Target Framework .NET Standard 2.0

A clear and concise description of what the bug is.

When I try to add the "using "WpfApp6ML.Model" to my WpfApp6 I get a "assembly or type not found error message" "type or namespace not found"

To Reproduce
Steps to reproduce the behavior:

1. Create a new WPF .Net project
2. Click Add "Machine Learning"
3. Verify the Project Properties , See what is created.
4. See error

Expected behavior
Targets should be consistent for the ML.NET projects that are added.

Screenshots
If applicable, add screenshots to help explain your problem.

Additional context
Add any other context about the problem here.

[JakeRadMSFT]

Resolved in #271