This is a re-land of #31561, after fixing performance regressions. Added change listening to the MouseTracker so that the Listener and tooltip can react to whether or not a mouse is connected at all. Added a change check to make sure Listener only repaints when something changed. Fixes #22817
microbenchmarks
To run these benchmarks on a device, first run `flutter logs' in one window to see the device logs, then, in a different window, run any of these:
flutter run --release lib/gestures/velocity_tracker_data.dart
flutter run --release lib/stocks/animation_bench.dart
flutter run --release lib/stocks/build_bench.dart
flutter run --release lib/stocks/layout_bench.dart
The results should be in the device logs.