[SB][ComposeIcons] Add OrderedIconSlotNamesRepository

Add a repository which will read config_statusBarIcons
and provide this as a StateFlow.

Bug: 418830269
Test: OrderedIconSlotNamesRepositoryTest
Flag: com.android.systemui.status_bar_system_status_icons_in_compose
Change-Id: I942da82618639d99f3cf6a3b984241c0718e19e6