Remove remaining private includes from scheduler headers (#58137)

Summary:
Pull Request resolved: #58137

Under the C++ Stable API RFC, `react/renderer/scheduler:scheduler` is a "for frameworks" module, but its exported headers still reached two private modules:

- `Scheduler.h` included `react/performance/timeline/PerformanceEntryReporter.h` and `react/renderer/observers/events/EventPerformanceLogger.h`. Both are only used as `std::shared_ptr` data members, so forward declarations are sufficient and the includes move to `Scheduler.cpp`.
- `SchedulerToolbox.h` included `react/renderer/leakchecker/LeakChecker.h` but never named anything from it. `leakchecker` is not even a dependency of the scheduler target, so the include is dead and is simply removed.

`react/renderer/observers/events:events` had no other header-level consumer in ReactCommon, so it is now cleanly private. `react/performance/timeline:timeline` is still reached from `RuntimeScheduler.h` and `NativePerformance.h`, which are handled separately.

After this, no scheduler header includes a private module directly.

Changelog: [Internal]

Reviewed By: javache

Differential Revision: D116909093

fbshipit-source-id: 84ecaf003d983034f2a1fa724a034c7050343443

Author: j-piasecki

packages/react-native/ReactCommon/react/renderer/scheduler/Scheduler.cpp

@@ -15,12 +15,14 @@
 #include <react/featureflags/ReactNativeFeatureFlags.h>
 #include <react/performance/cdpmetrics/CdpMetricsReporter.h>
 #include <react/performance/cdpmetrics/CdpPerfIssuesReporter.h>
+#include <react/performance/timeline/PerformanceEntryReporter.h>
 #include <react/renderer/animationbackend/AnimationBackend.h>
 #include <react/renderer/componentregistry/ComponentDescriptorRegistry.h>
 #include <react/renderer/core/EventQueueProcessor.h>
 #include <react/renderer/core/LayoutContext.h>
 #include <react/renderer/mounting/MountingOverrideDelegate.h>
 #include <react/renderer/mounting/ShadowViewMutation.h>
+#include <react/renderer/observers/events/EventPerformanceLogger.h>
 #include <react/renderer/runtimescheduler/RuntimeScheduler.h>
 #include <react/renderer/uimanager/LayoutEventEmitter.h>
 #include <react/renderer/uimanager/UIManager.h>

packages/react-native/ReactCommon/react/renderer/scheduler/Scheduler.h

@@ -16,14 +16,12 @@
 #include <vector>
 
 #include <ReactCommon/RuntimeExecutor.h>
-#include <react/performance/timeline/PerformanceEntryReporter.h>
 #include <react/renderer/componentregistry/ComponentDescriptorFactory.h>
 #include <react/renderer/core/ComponentDescriptor.h>
 #include <react/renderer/core/EventEmitter.h>
 #include <react/renderer/core/EventListener.h>
 #include <react/renderer/core/LayoutConstraints.h>
 #include <react/renderer/mounting/MountingOverrideDelegate.h>
-#include <react/renderer/observers/events/EventPerformanceLogger.h>
 #include <react/renderer/scheduler/InspectorData.h>
 #include <react/renderer/scheduler/SchedulerDelegate.h>
 #include <react/renderer/scheduler/SchedulerToolbox.h>
@@ -37,6 +35,8 @@ namespace facebook::react {
 
 class CdpMetricsReporter;
 class CdpPerfIssuesReporter;
+class EventPerformanceLogger;
+class PerformanceEntryReporter;
 class ViewTransitionModule;
 
 /*

packages/react-native/ReactCommon/react/renderer/scheduler/SchedulerToolbox.h

@@ -15,7 +15,6 @@
 #include <react/renderer/animationbackend/AnimationChoreographer.h>
 #include <react/renderer/componentregistry/ComponentDescriptorFactory.h>
 #include <react/renderer/core/EventBeat.h>
-#include <react/renderer/leakchecker/LeakChecker.h>
 #include <react/renderer/uimanager/UIManagerCommitHook.h>
 #include <react/renderer/uimanager/primitives.h>
 #include <react/utils/ContextContainer.h>