Pre load all icon drawables for QS tiles

This change is flag guarded. Preloading drawables improves performance in Compose and is needed for the QS refactor.

Test: manually
Test: local perfetto tracing
Flag: com.android.systemui.qs_ui_refactor_compose_fragment
Bug: 377290311
Change-Id: Ie70debb02f2d58e547d063f5c358286170f4c7b5