DO NOT MERGE Reduce chance of notification listener dropped messages.

The existing code for notification manager/listeners uses a oneway
binder api to deliver messages. One problem with this is that
notification objects can sometimes get fairly large, and can bump
into the oneway binder transaction buffer if many happen at once.

To reduce this issue, flip the service into a oneway delivery of
a status bar notification holder, whose wrapped content is then
immediately fetched upon receipt of the one-way message. This moves
the meat of the fetch to be over a two-way interface without changing
the properties of which object is actually sent (a tickle solution
with lookup key would have changed this)

Further research: attempt to chunk notification objects themselves.
They can sometimes transfer hundreds of KB over a binder transaction.

Bug: 15426276
Change-Id: Ib1a1f4ff848c16f80bcf2ae4dfd2b87a9091f0b2