Add Runnable mechanism to WakeupMessage

The WakeupMessage object provides a mechanism to create an Alarm
which will wake-up the device and deliver a message to a Handler.

Add a Runnable mechanism as an alternative to the message.

Bug: 67276378
Test: unit test
Change-Id: Icf5f03b2b25a340273f9d3fcd09f182216ea6238
2 files changed