Use display specific status bar window state

Before, NotificationShadeWindowViewController and others were always
retrieving the status bar window state from the default display, instead
of the one associated with the display where their view currently is.

Also makes StatusBarWindowStateController a PerDisplaySingleton instead
of SystemUISingleton, so that people are forced to think about displays
when trying to use the class.

Test: atest SystemUITests
Fixes: 420886625
Flag: com.android.systemui.shared.status_bar_connected_displays
Change-Id: I96011d2c82765174f02b11b702eb55d481072c20