refactor(slider): simplify hitSlop implementation

[devin-ai-integration]

Description

Simplify hitSlop implementation in both Slider components by using a number instead of an object when all directions are equal, following React Native's pattern and maintaining 48x48 hit target size.

Changelog

Slider/Incubator.Slider - Simplified hitSlop implementation while maintaining 48x48 hit target

Details

• Using number for hitSlop is simpler and follows React Native's pattern
• 12 pixels on each side maintains 48x48 hit target (24 + 12 + 12)
• No changes needed to z-index/touch priority as it's already handled correctly
• Tests verify the simplified hitSlop implementation
• Changes are backward compatible since React Native supports both forms

Link to Devin run: https://app.devin.ai/sessions/fc2cb153860345108b58985f0b922733

[devin-ai-integration]

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