Attach a new Worker to an application when it is created

Make Worker projects easier to set up in Objo Studio. When a user selects Worker in the Add Project dialog, Studio should ask which Command Line or Desktop application will use it, default to the current application, and include the new Worker automatically. This removes the easy-to-miss second trip to Project Settings while still allowing a Worker to be left unattached or associated with a different application in solutions containing multiple applications.