Display current extendible theme icon (2/3)

Consolidate relevant information about an icon style into an icon style
model, including the icon to display, to enable passing extendible theme
icon from the repository up to the binder. Also allow ShapeTileDrawable
to work with any icon drawable to accomodate extendible theme icon.

Flag: com.android.systemui.shared.extendible_theme_manager
Bug: 397782741
Test: manually verified
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:cfaa650472b642d7be8d42b5e5968ac49a0df1ab)
Merged-In: I47e403301602b0f0ce8289d4b8d2a9d30468c066
Change-Id: I47e403301602b0f0ce8289d4b8d2a9d30468c066