Stop non-tool A11yServices from injecting gestures onto sensitive views.

Sensitive views should continue responding to gestures injected by
Accessibility Tools.

Bug: 284180538
Flag: android.view.accessibility.prevent_a11y_nontool_from_injecting_into_sensitive_views
Test: atest AccessibilityEndToEndTest (CTS)
Test: atest MotionEventInjectorTest
Test: atest AccessibilityServiceConnectionTest
Test: Manual: Create a test service with isAccessibilityTool=true;
              dispatch a swipe gesture on the Settings >
	      Security & Privacy page; observe swipe is successful.
	      Repeat the above with isAccessibilityTool=false;
	      observe swipe is ignored.
Change-Id: I4298bb86062e25fa6c9e7f077a3016991d8cb91a