Listen for insets changes from MirroringDialog

The dialog was being shown only after lockscreen dismissal when an external display was connected.

The dialog got bottom insets only when created. However, when using 3 buttons nav the bottom insets was changing with some delay.

The base class (SystemUIBottomSheetDialog) now listens at insets changes and propagates them to child classes.

+ Adding a 200ms debounce to show the dialog: this avoids a visible jump when unlocking with 3 buttons nav.

Flag: None
Fixes: 327656078
Test: MirroringConfirmationDialogTest
Change-Id: I14ce1c2111707758f31ba9256a705edfd711b31e