Add FLAG_FORCE_CONSUMING_OPAQUE_CAPTION_BAR

Adds the flag to the InsetsSource created by the caption bar in shell,
and makes the DecorView consume the caption bar insets when set,
regardless of whether the caption bar is hidden or shown, as long as the
window is requesting opaque caption bars (i.e. did not set
APPEARANCE_TRANSPARENT_CAPTION_BAR_BACKGROUND)

Bug: 352563889
Flag: com.android.window.flags.enable_caption_compat_inset_force_consumption_always
Test: open non-immersive apps in freeform that don't handle caption bar
insets (Naver App, Spotify or OneDrive), check caption doesn't overlap
with app content
Test: atest DesktopModeWindowDecorationTests WindowDecorationTests
WindowInsetsTest InsetStateTest

Change-Id: Idb16f647f6a77e04b634e700b5345335b24d284d