Added display cutout handling to Shade Header in Flexiglass

The collapsed Shade Header is now split into two halves that are repositioned around the display cutout, like the old impl. Compose does not yet expose the actual bounding rectangle for the display cutout, so this needs to be derived from android.view.DisplayCutout and piped in from the root view for now. The display cutout bounds are provided via CompositionLocal to the entire Compose tree.

Bug: 298525212
Test: Manually verified header resizes and truncates content properly with different font/display sizes and cutout locations.
Change-Id: I8fa7fef39dcc920ce01c4ebb29e45aae310cdd87