[shade] hook ModernShadeCarrierGroupMobileView up to the shade colors

Add a couple of Binding classes that allow us to update the modern
status bar views without managing them from the controller directly.

Test: manual by changing dark theme in the shade
Test: ShadeHeaderControllerTest
Bug: 408937758
Flag: com.android.systemui.shade_header_blur_font_color
Change-Id: I020f6e74e28f44235eaf2afa38305445a5341665