Fix: allow screen readers to detect modal content

[flo-sch]

Hello @gorhom, thank you for this nice package :)

Here is a small contribution based on accessibility findings using TalkBack on Android and Voice Over on iOS.
If you are interested I could also port it to version 5

Motivation

In the project I work on, accessibility support is a requirement. I noticed a few issues when integrating <BottomSheetModal /> (we currently do not use <BottomSheet />):

1. Children cannot be read by Voice Over (iOS), only the modal itself is interpreted as a single "adjustable" view (my guess here is that elements with "accessibleRole: 'adjustable'" are not meant to have children? I could be wrong, this is just an assumption)
2. Text elements cannot be interpreted by Talk Back (Android) when using the default background, due to its accessibility props. This could easily be workaround by providing a custom background but I figured I could also propose this fix here.
3. I also face the issues described in [v4] When Talkback is enabled and a modal is displayed, the items below the modal sheet are still accessible by tap and the sheet is not focused #1641, but I did not manage to understand how to fix those myself unfortunately. I tried implementing some state in BottomSheetModalProvider (as initially proposed in [BottomSheetModal], a prop should allow elements below the sheet to not be accessible and the sheet should receive focus when presented #687), but since modals can be closed/dismissed in different ways, I could not implement a reliable state determining whether or not a modal is currently being presented (and adjust importantForAccessibility props based on that).

I recorded videos to illustrate what this PR fixes:

1. TalkBack

https://github.com/gorhom/react-native-bottom-sheet/assets/1577155/a7fa04c4-2e02-429a-a0f6-6e51d5644cd2
https://github.com/gorhom/react-native-bottom-sheet/assets/1577155/106c7c0c-c625-450a-ba29-3c34a3eb2927

2. Voice Over (unavailable in iOS simulator, but I used Accessibility Inspector instead)

https://github.com/gorhom/react-native-bottom-sheet/assets/1577155/dd0f8f89-71ec-49be-8d0a-09dd84943d6e
https://github.com/gorhom/react-native-bottom-sheet/assets/1577155/2d5ca920-d1e9-4afc-9b67-38122e016844

[Eli-Nathan]

I think this can currently be overridden by passing accessible={false} to the BottomSheet.
Accessibility was only just recently added back in to this repo so you may need to update to at least 4.6.0

#1288
Release notes

[flo-sch]

I think this can currently be overridden by passing accessible={false} to the BottomSheet.
Accessibility was only just recently added back in to this repo so you may need to update to at least 4.6.0

Hi @Eli-Nathan, setting accessible to false fixes it for VoiceOver only (iOS). I included that in this PR (or well, setting it to null which works as well)

I already tried 4.6.0 and 4.6.1

[github-actions]

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[flo-sch]

Un-stale

[thienautran]

I've been able to get focus to child elements by using accessible=false, however still haven't been able to figure out how to make elements behind the bottom sheet inert, either with BottomSheetModal or regular BottomSheet. Anyone have any ideas on how to fix this?

[flo-sch]

I believe it would require some implementation from this library first, as suggested there. At least I have not found any way to achieve that yet