Use larger frame of settings button for clicks

That way, the tappable area is of the minimum size. Additionally, set
the accessibility class name of the SettingsButton (now an ImageView) to
be Button, so the description matches the other buttons in the
FooterActions.

Test: manual
Test: Accessibility Scanner
Test: FooterActionsControllerTest
Fixes: 227536054
Change-Id: If412d7a5bdb53c363728f06e404fd70725b8c15a