mojo/discovery: Updating to latest v23 Java and switching
to have a single stream of updates with an enum field
indicating whether it is a lost or found update instead
of two separate found and lost streams.

This is more consistent with Discovery API in other languages
and also more consistent with similar Dart APIs such as
Syncbase's watch.

The old approach also made it easy to get into synchronization
issues since there is no ordering gaurantee between two
separate streams of data.

MultiPart: 1/2

Change-Id: I3832039fb3ebea172e99bb25af6e8f090b258380
16 files changed