iconActionPrevious  
  The drawable resource id for the notification action icon which allows users to cycle to the "previous" TorRuntime instance that is operating, upon click.
NOTE: This will not be utilized unless multiple instances of TorRuntime are operating within the service.
NOTE: Icons should be 24dp x 24dp for best performance.
Default: null (do not override default R.drawable.ic_kmp_tor_ui_action_previous)