[roll] Roll fuchsia [scenic][display] Keep track of currently used frame buffers.

When Scenic switches between DisplayCompositors and DisplaySwapchains,
since the DisplayController connection doesn't change, Vsync events
from old DisplaySwapchain may be forwarded to the new Swapchain in
the first or first few frames.

Previously (in fxrev.dev/532245) we just removed the DCHECK when
this occurs. However, this still affects current outstanding frames
(we still decrement the outstanding frames counter and flip to
another frame buffer). And this could cause display swapchain
to keep failing if there are *multiple* old Vsyncs handled by the
new Swapchain.

Instead, we should have a set keeping track of all the frame buffer
handles that are currently being used, and only handle Vsync events
if they contain image IDs from this set.

TEST: "fx shell session_control restart" on workstation.x64
      "fx shell sessionctl restart_session"

Original-Fixed: 77160
Original-Bug: 74677
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/588186
Original-Revision: 2e94286a3dd4dd5c65b42a6a57bce5b062bd202b
GitOrigin-RevId: 0aa3b757f7204baa6179e212f2989a125d0993c1
Change-Id: Iff0ba2e83c1a414190259b827750c8205661e2f1