Add long press button to autoclick panel

Initial commit for adding long press button to autoclick panel.
Actual long press logic will be implemented in a follow up cl.

Screenshot:
 - collapsed: go/screenshot-8rl4hfq4taxpjuq
 - expanded: go/screenshot-aipkmekdzf2evhf

Bug: 400744833
Test: atest AutoclickControllerTest, also manually verified in
      test devices.
Flag: com.android.server.accessibility.enable_autoclick_indicator
Change-Id: Ibc55562c57293519fe265e973cb19666f20097fa