feat(accessibility): forward importantForAccessibility prop

[vicprz]

Motivation

I have been focusing heavily on improving the accessibility of my application and encountered a few blocking issues on Android with the current implementation.

1. Focusable BottomSheetContent

By default, the entire BottomSheetContent was being treated as a single focusable element. This prevented screen readers from navigating inside the container to interact with individual components. While passing accessible={false} to BottomSheetModal resolved the issue on iOS, Android requires importantForAccessibility="no". This prop was not previously being forwarded by the library, so this PR adds that support.

2. Focusable Backdrop

I needed to prevent the backdrop from being focusable by screen readers since I have an explicit "Close" button inside the bottom sheet. Similar to the issue above, accessible={false} worked perfectly for iOS, but Android required importantForAccessibility="no". This PR brings that property to the backdrop component.

3. Consistency across components

For the sake of consistency, I also added importantForAccessibility prop forwarding to BottomSheetHandle, as it was the last remaining place where NullableAccessibilityProps were being utilized without it.