Extract event sending code into EventDispatcher.

Also combine event-sending code with what used to be the InjectedPointerTracker class because that class was used for sending events anyway.
Bug: 136131815:
Test: atest CtsAccessibilityTestCases  CtsAccessibilityServiceTestCases FrameworksServicesTests:TouchExplorerTest
Change-Id: I7fae3dc958642d8fae61b9120c732d27af16fca9
3 files changed