Make sure VRI waits for SV to draw before report

VRI is not currently waiting for SV to draw since SV may start its draw
before VRI opened the SyncSet. If that happens, VRI will not include SV
in its SyncSet and report draw finished even if SV is not complete.

This fix has SV create its own SyncSet when redrawNeeded. Then if VRI
creates a sync, SV will merge its own SyncSet into that one. If SV
already finished drawing, then nothing will get merged, but it means SV
is ready already. If SV is not finished, VRI will now also wait for SV's
draw to finish before calling finishDraw.

Test: Long delay in surfaceRedrawNeededAsync
Test: SurfaceSyncerTest
Bug: 230998394

Change-Id: I44331b8f54951e6dc633a4845bbf690abde0f95e