Mouse Keys Accessibility Feature

Creating mouse keys as a physical keyboard accessibility feature on Android.
If enabled, mouse keys will  allow users to use a physical keyboard to control
the mouse on the display.

Bug: 341799888
Test: atest FrameworksServicesTests:MouseKeysInterceptorTest
Flag: com.android.hardware.input.keyboard_a11y_mouse_keys
Change-Id: I49fa605375928f16180bbd9b3b63909f9261afbf