Feature to add njsproj, vcxproject etc with dotnet sln command

[ajithvcoder]

Is your feature request related to a problem? Please describe.

A clear and concise description of what the problem is. I am trying to use dotnet sln to add additional projects to sln file but it seems that it only supports .csproj

Describe the solution you'd like

A clear and concise description of what you want to happen. Include any alternative solutions you've considered. Add support to include .njsproj , .vcxproj etc

Additional context

Add any other context or screenshots about the feature request here.

[mastry]

In particular, the ability to add .esproj files with dotnet sln add would be very useful.