showCupertinoDialog should support barrierDismissible

[mehmetf]

Internal: https://b.corp.google.com/issues/145094605

In showCupertinoDialog it is not supported to enabled to dismiss the dialog on outside tap. It seems that this might be the normal iOS behaviour, but I couldn't find any documentation that it is not allowed to support it.

[alectogeek]

We realy need this feature!

[LongCatIsLooong]

I couldn't find anything that says this is not allowed, but from https://developer.apple.com/design/human-interface-guidelines/ios/views/alerts/ it shouldn't be encouraged either, as barrierDismissible = true makes it a lot easier for users to dismiss something important by mistake:

Minimize alerts. Alerts disrupt the user experience and should only be used in important situations like confirming purchases and destructive actions (such as deletions), or notifying people about problems. The infrequency of alerts helps ensure that people take them seriously. Ensure that each alert offers critical information and useful choices.

Sounds reasonable to add the parameter but set the default to false.

[tottomotto]

@xster,can you please share your thoughts on this.
I Implemented the change (defaulting to false) and I can make a PR if it's ok.

[xster]

Making it configurable (but defaulted to false) seems reasonable to me.

[github-actions]

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