fix(accessibility): Derive accessibilityTraits from role and state (#57515)

[cgoldsby]

Replaces the two independent writers on accessibilityTraits (one in C++ for role, one in ObjC for state) with a single deriveAccessibilityTraits() helper that rebuilds the full mask from None each commit.

On recycled Fabric views, the ObjC writer's diff guard can skip when the stale _props match the new props, leaving Selected and NotEnabled traits stale.

Fixes #57515

Changelog:

[IOS] [FIXED] - Derive accessibilityTraits from role and state in a single writer so Selected and NotEnabled traits are not lost on recycled Fabric views

Test Plan:

Reproducer repo: https://github.com/cgoldsby/rn-accessibility-traits-bug ([steps](https://github.com/cgoldsby/rn-accessibility-traits-bug#steps-to-reproduce-bug))

git clone https://github.com/cgoldsby/rn-accessibility-traits-bug.git
cd rn-accessibility-traits-bug
yarn install
cd ios && pod install && cd ..
yarn ios

1. Open Accessibility Inspector
2. Focus the target View
3. Tap "Toggle Role" to switch from role="button" to no role

Before fix: Selected trait is missing
After fix:

git apply patches/react-native+0.86.0.patch
cd ios && pod install && cd ..
yarn ios

Selected trait persists through the role change