Provides APIs for @c UIViews to communicate their elevation throughout the view hierarchy.
Used by @c MaterialElevationResponding instead of @c mdc_baseElevation.
This can be used in cases where there is elevation behind an object that is not part of the view hierarchy, like a @c UIPresentationController.
Note: If set to a negative value, this property is ignored as part of the @c mdc_baseElevation calculation.
@property (nonatomic, assign, unsafe_unretained, readwrite) CGFloat mdc_overrideBaseElevation;