Make a dotnet command

[sjh37]

Allow for this to be run using a dotnet command for .NET Core projects. That will allow you to generate from the command line, or a console application. The T4 code could even call the dotnet tool under the hood to do the heavy lifting, keeping the T4 template small. https://learn.microsoft.com/en-us/dotnet/core/tools/global-tools-how-to-create