[2/n] Improvements to AddressSpaceStream protocol

- Add a new state that represents the emulator rendering for sure.
- Avoid excessive notification spam.
- Add writeFullyAsync, writeFully that doesn't wait for finish.

This should be compatible with older hosts, but will notify old hosts
a bit more.

Bug: 177241396

Change-Id: Icfb00757a419f0b1328ff66eca39e51c566d8e11
3 files changed