fix: attachment preview list fixes

[isekovanic]

🎯 Goal

This PR fixes:

• Autoscrolling the newest attachment as we're adding
• Improves animations
• Adds shrinking animation of the FlatList when we're removing items

🛠 Implementation details

🎨 UI Changes

iOS

Before	After

Android

Before	After

🧪 Testing

☑️ Checklist

• I have signed the Stream CLA (required)
• PR targets the develop branch
• Documentation is updated
• New code is tested in main example apps, including all possible scenarios
  • SampleApp iOS and Android
  • Expo iOS and Android

[Stream-SDK-Bot]

SDK Size

title	develop	branch	diff	status
js_bundle_size	429 KB	429 KB	-29 B	🚀