Fix rounded list item focus outline disappearing on hover
Previously, list_item_rounded_background_selector.xml used a single
StateListDrawable (<selector>) to manage all interaction states. Because
the state_hovered item was defined above the state_focused item,
hovering over an already-focused list item would cause the selector to
match the hovered state first, replacing the focus outline ring with the
solid hover background.
This CL fixes the issue by wrapping the selectors in a <layer-list>.
The solid background overlays (hovered, pressed) are now handled
independently on a lower layer, while the focus ring outline is
handled on a higher layer. This ensures the focus ring remains
visible even when the icon is simultaneously being hovered or pressed.