SF: Add VsyncSchedule skeleton

Pull the Scheduler::VsyncSchedule struct and related code into its own
file, as it will be extended with more per-display state, e.g. reactor
registrations, resync state machine, etc.

Add <scheduler/Features.h> for feature flags. Move Scheduler into its
namespace.

Bug: 185535769
Test: libsurfaceflinger_unittest
Change-Id: I6e10893632c5abf40380df924791d1fcc27c3cc2
diff --git a/services/surfaceflinger/tests/unittests/TransactionApplicationTest.cpp b/services/surfaceflinger/tests/unittests/TransactionApplicationTest.cpp
index ec19100..16d4b59 100644
--- a/services/surfaceflinger/tests/unittests/TransactionApplicationTest.cpp
+++ b/services/surfaceflinger/tests/unittests/TransactionApplicationTest.cpp
@@ -26,7 +26,7 @@
 #include <log/log.h>
 #include <ui/MockFence.h>
 #include <utils/String8.h>
-#include "TestableScheduler.h"
+
 #include "TestableSurfaceFlinger.h"
 #include "mock/MockEventThread.h"
 #include "mock/MockVsyncController.h"
@@ -85,11 +85,8 @@
                                 std::move(eventThread), std::move(sfEventThread));
     }
 
-    TestableScheduler* mScheduler;
     TestableSurfaceFlinger mFlinger;
 
-    std::unique_ptr<mock::EventThread> mEventThread = std::make_unique<mock::EventThread>();
-
     mock::VsyncController* mVsyncController = new mock::VsyncController();
     mock::VSyncTracker* mVSyncTracker = new mock::VSyncTracker();
     mock::MockFence* mFenceUnsignaled = new mock::MockFence();