SF: Unify data types for display modes

Remove the RefreshRateConfigs::RefreshRate wrapper around DisplayMode.
Store DisplayModes as a SmallMap, so that RefreshRateConfigs uses the
same data structure for lookup by ID. Use iterators into that map for
all bookkeeping in RefreshRateConfigs.

Bug: 182939859
Bug: 185535769
Test: libsurfaceflinger_unittest
Change-Id: I7708fa997089802c45d906b17b7a073f5c82105e
diff --git a/services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.h b/services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.h
index 3186d6d..4923031 100644
--- a/services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.h
+++ b/services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.h
@@ -29,6 +29,7 @@
 
 namespace android::scheduler {
 
+class TimeKeeper;
 class VSyncTracker;
 
 // VSyncDispatchTimerQueueEntry is a helper class representing internal state for each entry in