A11y: autoclickScrollPanel - Add Button Hover listeners

* Add ScrollPanelControllerInterface to handle scroll operations.
* Add button hover listeners for direction buttons and exit buttons.

Video: http://shortn/_LfNmMSm8VC

Bug: b/388845488
Test: AutoclickControllerTest
Flag: com.android.server.accessibility.enable_autoclick_indicator
Change-Id: I50deaa83835d8943d37c19c1266549f0a0ff493e