fix(iOS): Verify that ScrollView gesture hasn't begun when triggering pan gesture

[kmichalikk]

Closes https://github.com/software-mansion/react-native-screens-labs/issues/489

Description

This PR addresses the issue that, when using custom PanGestureRecognizer on iOS 26 (for handling custom animations on swipe) with a screen that has a horizontal ScrollView, and when swiping for the second time before the view stopped scrolling, the screen is popped with pan gesture.

Changes

Added check for ScrollGestureRecognizer state=Began in shouldRecognizeSimultaneouslyWithGestureRecognizer to return NO.

before	after
sv-custom-horizontal-bad.mov	sv-custom-horizontal-good.mov

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Test code and steps to reproduce

Use Test3265 on iOS 26; make sure that the screen has animation set to custom animation and animationMatchesGesture: true.