[Sb] Add background and foreground support to icon tints

This CL adds the possibility to tint a status bar icon with both a
background and foreground color. It does this by making the following
changes:

1. Add support for tint and foregroundColor in TintedIconManager
2. Define contrasting colors for DarkIconDispatcher, and add a new
   callback that exposes them
3. Support a new interface method (with a default impl) on
   StatusIconDisplayable that can accept the foreground tint

As of now, there are no clients of this new tint color. Follow-up CLs
will implement usage on ModernStatusBarMobileView.

Test: compile
Test: visually inspect that icons are the same color
Test: check dumpsys for information from DarkIconDispatcher
Bug: 270385675
Change-Id: I3280ba7839d7b351ea97e0cb42e2450c0b4b935b