Provide dotnet cli extension

[kzu]

Which would basically do dotnet msbuild build.proj /t:COMMAND:

dotnet cli	becomes
dotnet corebuild configure	dotnet msbuild build.proj /t:configure
dotnet corebuild build	dotnet msbuild build.proj /t:build
dotnet corebuild test	dotnet msbuild build.proj /t:test
dotnet corebuild run	dotnet msbuild build.proj /t:run

[kzu]

Additional inspiration from xunit cli and the dotnet muxer