Making sure shade doesn't open after unfolding when no security is set

Shade was opening because `mKeyguardStateController.isShowing()` is false when screen is off but no security set. I changed the logic of isShadeOpen to actually say if shade is open instead of being always true on keyguard and made small fixes to the logic in CentralSurfaces. We want to keep shade open only when we're in unlocked (SHADE) state.

Added isShadeOpen method to NPVC - it should be helpful for other use cases and might be less confusing to use than isFullyExpanded.

Fixes: 259012717
Test: manual -> set security to none -> turn screen off in folded mode -> unfold -> see launcher instead of shade
Test: NotificationPanelViewControllerTest
Change-Id: I5c1ce04fac5e549a49a53bd409c6e198483b4647