feat(android): support alarm manager for trigger notifications

[helenaford]

Alpha release published 1.9.0-alpha.0

New Timestamp Trigger API:

{
   ...
  alarmManager: true | {
     allowWhileIdle: true
  }
}

E.G. (example here):

{
   timestamp: date,
   type: TriggerType.TIMESTAMP,
   alarmManager: {
     allowWhileIdle: true
   }
 }