Add missing OS and Arch at dotnet publish

[ITaluone]

Closes #1350

I don't know how to add the requested Target property..

@matkoch If you can give me a hint how to add it, I will add it :)

I confirm that the pull-request:

• Follows the contribution guidelines
• Is based on my own work
• Is in compliance with my employer

[ArwynFr]

Perhaps this ?

{
  "name": "Target",
  "type": "string",
  "format": "/t:{value}",
  "help": "..."
}

[ITaluone]

Hmm.. I don't know.. if I run dotnet publish --help it doesn't output a Target switch, btw.