Add barrierColor property to showCupertinoDialog (#166911)

implimented https://github.com/flutter/flutter/issues/166910



https://github.com/user-attachments/assets/fe9aa2ce-b8a5-4458-b04a-781763959169

## How to Verify
- Set enableDrag: false in CupertinoSheetRoute or showCupertinoSheet.

```diff

showCupertinoDialog<void>(
      context: context,
+      barrierColor: CupertinoColors.activeOrange.withValues(alpha: 0.5),
      builder:
          (BuildContext context) => CupertinoAlertDialog(
            title: const Text('Alert'),
            content: const Text('Proceed with destructive action?'),
            actions: <CupertinoDialogAction>[
              CupertinoDialogAction(
                /// This parameter indicates this action is the default,
                /// and turns the action's text to bold text.
                isDefaultAction: true,
                onPressed: () {
                  Navigator.pop(context);
                },
                child: const Text('No'),
              ),
              CupertinoDialogAction(
                /// This parameter indicates the action would perform
                /// a destructive action such as deletion, and turns
                /// the action's text color to red.
                isDestructiveAction: true,
                onPressed: () {
                  Navigator.pop(context);
                },
                child: const Text('Yes'),
              ),
            ],
          ),
    );

```

- The following is a screenshot of
`examples/api/lib/cupertino/dialog/cupertino_alert_dialog.0.dart` after
adding `barrierColor: CupertinoColors.activeOrange.withValues(alpha:
0.5),`.

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [ ] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

<!-- Links -->
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[Tree Hygiene]:
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[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
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[Features we expect every widget to implement]:
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[CLA]: https://cla.developers.google.com/
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[breaking change policy]:
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[Discord]:
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[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

packages/flutter/lib/src/cupertino/route.dart

@@ -1410,6 +1410,7 @@ Future<T?> showCupertinoDialog<T>({
   required BuildContext context,
   required WidgetBuilder builder,
   String? barrierLabel,
+  Color? barrierColor,
   bool useRootNavigator = true,
   bool barrierDismissible = false,
   RouteSettings? routeSettings,
@@ -1422,7 +1423,7 @@ Future<T?> showCupertinoDialog<T>({
       context: context,
       barrierDismissible: barrierDismissible,
       barrierLabel: barrierLabel,
-      barrierColor: CupertinoDynamicColor.resolve(kCupertinoModalBarrierColor, context),
+      barrierColor: barrierColor,
       settings: routeSettings,
       anchorPoint: anchorPoint,
       requestFocus: requestFocus,

packages/flutter/test/cupertino/dialog_test.dart

@@ -1737,6 +1737,60 @@ void main() {
     semantics.dispose();
   });
 
+  testWidgets('showCupertinoDialog - custom barrierColor', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      CupertinoApp(
+        home: Builder(
+          builder: (BuildContext context) {
+            return Center(
+              child: Column(
+                children: <Widget>[
+                  CupertinoButton(
+                    child: const Text('Custom BarrierColor'),
+                    onPressed: () {
+                      showCupertinoDialog<void>(
+                        context: context,
+                        barrierColor: Colors.red,
+                        builder: (BuildContext context) {
+                          return CupertinoAlertDialog(
+                            title: const Text('Title'),
+                            content: const Text('Content'),
+                            actions: <Widget>[
+                              const CupertinoDialogAction(child: Text('Yes')),
+                              CupertinoDialogAction(
+                                child: const Text('No'),
+                                onPressed: () {
+                                  Navigator.pop(context);
+                                },
+                              ),
+                            ],
+                          );
+                        },
+                      );
+                    },
+                  ),
+                ],
+              ),
+            );
+          },
+        ),
+      ),
+    );
+
+    await tester.tap(find.text('Custom BarrierColor'));
+    await tester.pumpAndSettle();
+    expect(tester.widget<ModalBarrier>(find.byType(ModalBarrier).last).color, equals(Colors.red));
+
+    await tester.tap(find.text('No'));
+    await tester.pumpAndSettle();
+    expect(
+      find.byWidgetPredicate(
+        (Widget widget) => widget is ModalBarrier && widget.color == Colors.red,
+      ),
+      findsNothing,
+    );
+  });
+
   testWidgets('CupertinoDialogRoute is state restorable', (WidgetTester tester) async {
     await tester.pumpWidget(
       const CupertinoApp(restorationScopeId: 'app', home: _RestorableDialogTestWidget()),