[amazon-fireos]dialogs plugin's confirm and prompt methods dont work

confirm method has platform check and amazon-fireos is missing. Need to add it.
prompt method throws runtime exception. Here is why:
prompt() method is executed in a worker thread that does not have a message queue(or Looper object) associated with it and hence "can't create a handler" exception is thrown. To fix this issue, we need to create the EditText widget from within the UI thread.