fix: iOS honor RCTI18nUtil RTL on New Architecture

[kashmiry]

Summary:

On the New Architecture (Fabric) on iOS, the slider follows the device language instead of the app's language.
So if the app is in (RTL) and forced with:

I18nManager.forceRTL(true)

but the device is in English (LTR), the slider appears flipped — the filled side and drag direction don't match the rest of the app's UI. Same problem in reverse: English app on an Arabic device.

This fix makes the slider follow the app's direction (I18nManager.forceRTL) regardless of what the device is set to.

• Android already works correctly, so no changes there.
• The old architecture (Paper) is unaffected.

issue.mov

fixed.mov

Test Plan:

Tested on the New Architecture (Fabric) on iOS with all four combinations of device locale × app forced direction. The slider's filled track grows from the value-minimum side as defined by the app's direction in every case:

Device locale	App forced direction	Expected filled-from-side	Result
LTR (en_US)	LTR	Left	✅
LTR (en_US)	RTL (forceRTL(true))	Right	✅
RTL (ar_SA)	LTR (forceRTL(false))	Left	✅
RTL (ar_SA)	RTL	Right	✅

Also verified:

• Dragging toward the maximum side increases the value, regardless of device locale.
• tapToSeek taps land at the correct value in all four combinations.
• The inverted prop still works on top of the new baseline direction.
• No regressions on Android.

Repro steps (before the fix):

1. Run on iOS with New Architecture enabled.
2. Ensure iOS project has a localized Info.plist example for Arabic (RTL language)
3. Set device language to English; in the app, call I18nManager.forceRTL(true) and restart.
4. Observe the slider's filled track is on the left (incorrect — should be on the right to match the app's RTL UI).
5. Apply this patch, rebuild, and observe the filled track is now on the right.