Move FlagManager to a common SF lib

So that CompositionEngine can use it.

Bug: 236745178
Test: builds
Change-Id: Ib873cb4a0b4231723a22fbc8fa22ec955aa6f329
diff --git a/services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.cpp b/services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.cpp
index 3e7ec49..ef30887 100644
--- a/services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.cpp
+++ b/services/surfaceflinger/Scheduler/VSyncDispatchTimerQueue.cpp
@@ -25,7 +25,7 @@
 
 #include <scheduler/TimeKeeper.h>
 
-#include "FlagManager.h"
+#include <common/FlagManager.h>
 #include "VSyncDispatchTimerQueue.h"
 #include "VSyncTracker.h"