Create a VsyncSchedule per display

In order to determine the vsync offsets between displays, keep track of
a VsyncSchedule for each display.

Store the VsyncSchedules in a SmallMap. Update getVsyncSchedule with a
parameter to choose the display. The default parameter uses the leader's
display, which is what current external callers want.

Update VsyncDispatches when the leader changes, so that they are always
listening to the leader.

Enable and disable vsync callbacks per display. Earlier attempts to turn
them on and off together could leave a secondary display on a bad
schedule. Move state and logic for enabling/disabling the callbacks into
VsyncSchedule. Add a method for resyncing all displays at once.

Use std::shared_ptrs for VsyncDispatches. This prevents lifetime issues
if a VsyncSchedule gets removed while its VsyncDispatch is still in use.
Same for VsyncTracker, which is referenced by VsyncDispatch.

When the leader VsyncSchedule changes, call cancel on
VsyncCallbackRegistrations and replace them with new ones using the new
VsyncDispatches. If a callback was scheduled, schedule a new one.

Update VsyncSchedule's members' traces so that there is a separate track
for each display.

Move SF's record of the last HWC Vsync states into VsyncSchedule, so it
sits with other related logic. Remove the pending HWC Vsync state, which
did not affect behavior.

For refresh rate changes, modulate vsync config based on the leader
display. When switching leaders, force a period transition to ensure
that a potential refresh rate change is completed.

Bug: 255601557
Bug: 256196556
Bug: 241285473
Bug: 241286146
Test: libsurfaceflinger_unittest
Test: manual (look at perfetto traces)
Change-Id: If60218e85292c786b9fa70ecb33ee374d3a385e0