[Feature request] Add scroll deceleration factor

Hi there! Currently, GestureSettings exposes scrollDecelerationEnabled to control whether a deceleration animation occurs after a user finishes a scroll/pan gesture. While this flag works as expected on Android to toggle the fling/inertia effect, it has no effect on iOS.

When a user scrolls the map on iOS, the map continues coasting for a significant amount of time before coming to a complete stop. This takes longer than expected compared to native iOS scrolling behaviors, and there is currently no way to disable or fine-tune this deceleration via the Flutter plugin.

It looks like in the native Mapbox iOS SDK, this behavior is managed via GestureOptions.panDecelerationFactor (I could be wrong). It would be a great to have native deceleration tuning in Flutter.

Thank you in advance

https://github.com/user-attachments/assets/cc0fbf68-6612-460a-b361-39f62309bd3b

Beginne mit der GestureSettings API des Flutter-Plugins und verfolge, wie scrollDecelerationEnabled an die iOS-Implementierung übergeben wird. Prüfe, ob panDecelerationFactor im nativen Mapbox iOS SDK der relevante Einstiegspunkt ist, definiere anschließend die Flutter-seitige Steuerung und verifiziere, dass sie das Auslaufverhalten der iOS-Karte ändert, ohne Android zu beeinträchtigen.