[roll] Roll fuchsia [goldfish] Integrate sync device with goldfish display.

Previously, we always assumed that display ColorBuffers are
displayed immediately after posted, and we send OnVsync events
to clients based on this assumption. However, rcFbPost operation
on host could take some time as well, and this could make pending
|rcFbPost| commands accumulate in the pipe, causing performance
issues like fxb/67425.

This change solves the issue by introducing goldfish Sync device to
display. After each rcFbPost() command, we create a goldfish
sync object on host, and start an async wait until host finishes
posting the FrameBuffer. The |images| field in OnVsync() event
won't be updated until the sync object is signalled, which
ensures clients always use FrameBuffers not being used by host,
and provides a flow control mechanism for goldfish display.

The Vsync signals sent from the display driver are still "simulated"
by Fuchsia -- This matches other guest systems' current presenting
behaviors (e.g. goldfish-opengl/system/hwc2/EmuHWC2.cpp for Android)
and could provide a steady OnVsync event flow for clients. We could
replace them with host pipe-based hardware signals once we have them
implemented on host.

Original-Bug: 65038
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/498998
Original-Revision: 3593774b429f843b19fa16c0e31b79907fce6297
GitOrigin-RevId: 0ffa73e100f3c9da1555b5279f02db1286fcea0f
Change-Id: I55fb9df36c4a0b02705877fc486fa98bcd53ebf9