[XPD] Provide state_has_icon_space drawable state

This change applies to Preferences that implement DrawableStateLayout
(or more specifically, Preferences whose layout's root view's class
implements DrawableStateLayout), and provides a new state,
"R.attr.state_has_icon_space".

The new state is a boolean that is true if and only if the Preference
has a visible icon frame.

This new state can, optionally, be conditioned against by the provided
DrawableStateLayout background of the preference (see change
I9597b867109de218b323f469a4dfbcc30d2564b5).

Test: manual
Relnote: N/A
Flag: com.android.settingslib.widget.theme.flags.is_expressive_design_enabled
Bug: 375480009
Change-Id: I501ee49d0010c19f874a743a8730d6f58996e6fc