[WindowManager] Add PRIVATE_FLAG_COLOR_SPACE_AGNOSTIC.

Normally on a phone, there are a bunch of layers that can be considered color
space agnostic, for example NavigationBar and ScreenDecorOverlay*. Previously
we added a SurfaceControl API setColorSpaceAgnostic to allow a surface to tell
SurfaceFlinger it's color space agnostic, this patch adds a private flag in
window manager to allow views to set it via WindowManager.LayoutParams, window
manager will process this private flag and call setColorSpaceAgnostic when it's
changed.

BUG: 126616348
Test: Build, flash and boot. Use UIBench to check WCG behaviour
Change-Id: Iecee6528c86c390c70379bbc05b114c53d0cca48