Different easing curves for x-axis and y-axis in layer scaling animation

[BokunoMasayume]

Issue Description:

When different easing curves are applied to the x-axis and y-axis of a layer's scaling animation, the animation behavior ignores the y-axis curve description. Both axes end up using the x-axis curve description, resulting in animation performance that doesn't match expectations.

Relevant code locations:

KeyframeData parsing: https://github.com/airbnb/lottie-ios/blob/master/Sources/Private/Model/Keyframes/KeyframeData.swift#L95
Curve control point parsing : https://github.com/airbnb/lottie-ios/blob/master/Sources/Private/Utility/Primitives/VectorsExtensions.swift#L86

Same issue on Lottie-android: airbnb/lottie-android#2655