Make sendHint private in platform

 * Convert PerformanceHintManager sendHint to a private API
 * Have HWUI depend on private implementation

Bug: b/261640114
Test: atest PerformanceHintNativeTestCases
Test: atest FrameworksCoreTests:android.os.PerformanceHintManagerTest

Change-Id: Ic65eef1fbd1c26040e86ddf3cf7c59581fee4374
6 files changed