DarkIconRepository: add display id parameter

This allows the repository to expose the display specific dark changes.

Test: NotificationIconContainerStatusBarViewModelTest.kt
Test: Manually - Start light/dark themed activities on both displays
Bug: 369337696
Flag: com.android.systemui.status_bar_connected_displays
Change-Id: I92f3866f711e4008f2f5f41ffcc995dc981757b1