Update iconView in biometric prompt to act as a button

When face succeeds during biometric prompt coex, the icon button should
act as a button to support switch and voice access.

Test: verified button works with switch access
Bug: 359394944
Bug: 359423579
Flag: com.android.systemui.bp_icon_a11y
Change-Id: Ifad01107922ac22e78185f17e4aa3203776566f8