Add focus outline to overview clear all button

Use the same class BorderAnimator in TaskView to draw focus outline with padding between button and outline as UX design

Bug: 324911125
Test: Manual, launcher overview, use keyboard left arrow to show clear all button, outline should be shown
Flag: LEGACY ENABLE_KEYBOARD_QUICK_SWITCH ENABLED
Change-Id: I62ac2ce7a8f62170421b4318c9fa58805384187b