Fix: Pressable regular border radius rendering on iOS on old arch (#3279

)

## Description

<!--
Description and motivation for this PR.

Include 'Fixes #<number>' if this is fixing some issue.
-->

Fixes #3137 

This PR fixes **regular** border rendering for gesture handler buttons
on old architecture. React Native
[determines](https://github.com/facebook/react-native/blob/main/packages/react-native/React/Views/RCTViewManager.m#L370-L377)
how native component handles border radius by checking if it implements
`setBorderRadius` method. Previously, there was not a mechanism to scale
border radius down and it relied purely on how the iOS handles it for
large values.

It is done similarly to how [react
native](https://github.com/facebook/react-native/blob/main/packages/react-native/React/Views/RCTView.m#L670-L734)
calculates that but for regular borders only it becomes much simpler.


![example](https://github.com/user-attachments/assets/377a8f5e-af1d-4095-a193-62715f860c70)

## Test plan

<!--
Describe how did you test this change here.
-->

<details>

<summary>Test code</summary>

```ts
import React from 'react';
import {
  View,
  Text,
  SafeAreaView,
  Pressable as RNPressable,
} from 'react-native';

import {
  Pressable as RNGHPressable,
  GestureHandlerRootView,
} from 'react-native-gesture-handler';

const examples = new Array(16).fill(0).map((_, i) => i);

function DefaultPressables() {
  return (
    <View>
      <Text>RN</Text>
      <View style={{ gap: 8 }}>
        {
          examples.map((i) => (
            <RNPressable
              key={`rn_${i}`}
              style={[
                buttonStyle,
                {
                  backgroundColor: 'lightgreen',
                  borderRadius: i,
                },
              ]}>
              <Text>{i}</Text>
            </RNPressable>
          ))
        }

        <RNPressable
          style={[
            buttonStyle,
            {
              backgroundColor: 'lightgreen',
              borderRadius: 999,
            },
          ]}>
          <Text>999</Text>
        </RNPressable>
      </View>
    </View>
  )
}

function GHPressables() {
  return (
    <View>
      <Text>RNGH</Text>
      <View style={{ gap: 8 }}>
      {
          examples.map((i) => (
            <RNGHPressable
              key={`rngh_${i}`}
              style={[
                buttonStyle,
                {
                  backgroundColor: 'lightgreen',
                  borderRadius: i,
                },
              ]}>
              <Text>{i}</Text>
            </RNGHPressable>
          ))
        }

        <RNGHPressable
          style={[
            buttonStyle,
            {
              backgroundColor: 'lightgreen',
              borderRadius: 999,
            },
          ]}>
          <Text>{999}</Text>
        </RNGHPressable>
      </View>
    </View>
  )
}


export default function App() {
  return (
    <GestureHandlerRootView style={{ flex: 1 }}>
      <SafeAreaView>
        <View style={{ padding: 16, gap: 8, flexDirection: 'row' }}>
          <DefaultPressables />
          <GHPressables />
        </View>
      </SafeAreaView>
    </GestureHandlerRootView>
  );
}

const buttonStyle = {
  width: 32,
  height: 32,
  alignItems: 'center',
  justifyContent: 'center',
};
```

</details>

apple/RNGestureHandlerButton.h

@@ -26,6 +26,7 @@
  *  Insets used when hit testing inside this view.
  */
 @property (nonatomic, assign) UIEdgeInsets hitTestEdgeInsets;
+@property (nonatomic, assign) CGFloat borderRadius;
 @property (nonatomic) BOOL userEnabled;
 
 #if TARGET_OS_OSX && RCT_NEW_ARCH_ENABLED

apple/RNGestureHandlerButton.mm

@@ -89,6 +89,29 @@ - (RNGHUIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
   }
   return inner;
 }
+
+- (void)setBorderRadius:(CGFloat)radius
+{
+  if (_borderRadius == radius) {
+    return;
+  }
+
+  _borderRadius = radius;
+  [self.layer setNeedsDisplay];
+}
+
+- (void)displayLayer:(CALayer *)layer
+{
+  if (CGSizeEqualToSize(layer.bounds.size, CGSizeZero)) {
+    return;
+  }
+
+  const CGFloat radius = MAX(0, _borderRadius);
+  const CGSize size = self.bounds.size;
+  const CGFloat scaleFactor = RCTZeroIfNaN(MIN(1, size.width / (2 * radius)));
+  const CGFloat currentBorderRadius = radius * scaleFactor;
+  layer.cornerRadius = currentBorderRadius;
+}
 #endif
 
 #if TARGET_OS_OSX && RCT_NEW_ARCH_ENABLED