[DesktopStatusBar] Make the shadeOverlays behave like desktop panels

Changes the touchable region for the ShadeWindow when DualShade
is enabled on desktop. The touchable region is restricted to the
ShadeOverlay bounds when only an overlay is visible. When inside
a scene, everything except the status bar area is touchable.

Bug: 438498963
Test: Manual
Test: new Unit tests
Flag: com.android.systemui.status_bar_for_desktop
Change-Id: I9f2b1d74c726842ffb1b35d1ff82f7ea241d71a2