Implement class to evaluate current use of Notification object memory

This evaluates the size of Notification objects in memory and emits the sizes to bugreport. The change is flag guarded.

Bug:194112194
Bug:235451049

Test: Unit tests added.

Change-Id: Iab91f35b77cf8acc07fe3466656ae3cab26a295b
Merged-In: Ie385e74b672f6755cec51b2046243d0c5dad43ee
Merged-In: Iab91f35b77cf8acc07fe3466656ae3cab26a295b