feat: add a headerBackAccessibilityLabel option in stack

closes #9016

packages/stack/src/types.tsx

@@ -145,6 +145,10 @@ export type StackHeaderOptions = {
    * Whether back button title font should scale to respect Text Size accessibility settings. Defaults to `false`.
    */
   headerBackAllowFontScaling?: boolean;
+  /**
+   * Accessibility label for the header back button.
+   */
+  headerBackAccessibilityLabel?: string;
   /**
    * Title string used by the back button on iOS. Defaults to the previous scene's `headerTitle`.
    * Use `headerBackTitleVisible: false` to hide it.

packages/stack/src/views/Header/HeaderSegment.tsx

@@ -162,6 +162,7 @@ export default function HeaderSegment(props: Props) {
     headerBackTitleVisible,
     headerTruncatedBackTitle: truncatedLabel,
     headerPressColorAndroid: pressColorAndroid,
+    headerBackAccessibilityLabel: backAccessibilityLabel,
     headerBackAllowFontScaling: backAllowFontScaling,
     headerTitleAllowFontScaling: titleAllowFontScaling,
     headerTitleStyle: customTitleStyle,
@@ -290,6 +291,7 @@ export default function HeaderSegment(props: Props) {
     ? left({
         backImage,
         pressColorAndroid,
+        accessibilityLabel: backAccessibilityLabel,
         allowFontScaling: backAllowFontScaling,
         onPress: onGoBack,
         labelVisible: headerBackTitleVisible,