Make SysUiState for external display an override of the default one

SysUI state has several types of flags. Some of them are meant to be
device specific (e.g. SYSUI_STATE_AWAKE), and some of them display
specific (SYSUI_STATE_QUICK_SETTINGS_EXPANDED)

This cl leaves the default display SysUIState instance as it was, but it
 introduces the concept of "SysUIStateOverride" for external displays.

If a bit has been set in the override state, it will override the same
in the default display. All bits that have never been overridden wil
still have the value from the default display.

Bug: 362719719
Bug: 398011576
Test: SysUIStateOverrideTest
Flag: com.android.systemui.shade_window_goes_around
Change-Id: I3927a1fdd45afab4fd85b4bd9a8dc60e93c3ff3d