[Dual Shade] Include the shade header clock in the highlight chip.

Bonus 1: Consolidate the highlight chip implementations into a single
composable.

Bonus 2: Change the clock color based on the highlight chip theme.

Fix: 418136012
Fix: 417536497
Test: Manually tested by opening the notifications shade on an unfolded
 device and observing the shade header clock appears as expected.
Flag: com.android.systemui.scene_container
Change-Id: If90c1ccacdd62c68b232a64fbd40688b37ea33e3