title: Set default project in solution for dotnet run
body: <p>I have created a solution and a webapi project in it's own folder.
  I have then added the project to the solution.</p>
  
  <p>I would like to be able to run <code>dotnet run</code> without specifying the project by setting a default (Like i would in Visual Studio)</p>
  
  <p>Is this possible or not yet doable with the CLI?</p>