Added "PreferMonitor" and "MonitorIndex" to control what monitor apps are toggled on.

The setting is available at the root config level, and can be overridden per application.

{
  "PreferMonitor": "WithCursor", // WithCursor | Primary | AtIndex
  "MonitorIndex": 0,

  "Apps": [
    {
      "PreferMonitor": "WithCursor", // WithCursor | Primary | AtIndex
      "MonitorIndex": 0,
    }
  ]
}