Add ability to disable CupertinoSegmentedControl (#152813)

### Summary

Add the ability to configure enabled or disabled segments in CupertinoSegmentedControl. The idea is to pass a `segmentStates` map, where the user can set the state according to segment key. User can also set background and text colors when the segment is disabled.

### Demo

https://github.com/user-attachments/assets/4a02da02-a0fb-4ded-a271-033a8dc79ac3

### Related issue
Fixes https://github.com/flutter/flutter/issues/52105

examples/api/lib/cupertino/segmented_control/cupertino_segmented_control.0.dart

@@ -37,6 +37,9 @@ class SegmentedControlExample extends StatefulWidget {
 
 class _SegmentedControlExampleState extends State<SegmentedControlExample> {
   Sky _selectedSegment = Sky.midnight;
+  bool _toggleOne = false;
+  bool _toggleAll = true;
+  Set<Sky> _disabledChildren = <Sky>{};
 
   @override
   Widget build(BuildContext context) {
@@ -45,6 +48,7 @@ class _SegmentedControlExampleState extends State<SegmentedControlExample> {
       navigationBar: CupertinoNavigationBar(
         // This Cupertino segmented control has the enum "Sky" as the type.
         middle: CupertinoSegmentedControl<Sky>(
+          disabledChildren: _disabledChildren,
           selectedColor: skyColors[_selectedSegment],
           // Provide horizontal padding around the children.
           padding: const EdgeInsets.symmetric(horizontal: 12),
@@ -73,9 +77,60 @@ class _SegmentedControlExampleState extends State<SegmentedControlExample> {
         ),
       ),
       child: Center(
-        child: Text(
-          'Selected Segment: ${_selectedSegment.name}',
-          style: const TextStyle(color: CupertinoColors.white),
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: <Widget>[
+            Text(
+              'Selected Segment: ${_selectedSegment.name}',
+              style: const TextStyle(color: CupertinoColors.white),
+            ),
+            const SizedBox(height: 20),
+            Row(
+              mainAxisSize: MainAxisSize.min,
+              children: <Widget>[
+                const Text('Disable one segment', style: TextStyle(color: CupertinoColors.white)),
+                CupertinoSwitch(
+                  value: _toggleOne,
+                  onChanged: (bool value) {
+                    setState(() {
+                      _toggleOne = value;
+                      if (value) {
+                        _toggleAll = false;
+                        _disabledChildren = <Sky>{Sky.midnight};
+                      } else {
+                        _toggleAll = true;
+                        _disabledChildren = <Sky>{};
+                      }
+                    });
+                  },
+                ),
+              ],
+            ),
+            Row(
+              mainAxisSize: MainAxisSize.min,
+              children: <Widget>[
+                const Text('Toggle all segments', style: TextStyle(color: CupertinoColors.white)),
+                CupertinoSwitch(
+                  value: _toggleAll,
+                  onChanged: (bool value) {
+                    setState(() {
+                      _toggleAll = value;
+                      if (value) {
+                        _toggleOne = false;
+                        _disabledChildren = <Sky>{};
+                      } else {
+                        _disabledChildren = <Sky>{
+                          Sky.midnight,
+                          Sky.viridian,
+                          Sky.cerulean,
+                        };
+                      }
+                    });
+                  },
+                ),
+              ],
+            ),
+          ],
         ),
       ),
     );

examples/api/test/cupertino/segmented_control/cupertino_segmented_control.0_test.dart

@@ -2,10 +2,43 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter/cupertino.dart';
 import 'package:flutter_api_samples/cupertino/segmented_control/cupertino_segmented_control.0.dart' as example;
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
+  testWidgets('Verify initial state', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      const example.SegmentedControlApp(),
+    );
+
+    // Midnight is the default selected segment.
+    expect(find.text('Selected Segment: midnight'), findsOneWidget);
+
+    // All segments are enabled and can be selected.
+    await tester.tap(find.text('Viridian'));
+    await tester.pumpAndSettle();
+    expect(find.text('Selected Segment: viridian'), findsOneWidget);
+
+    await tester.tap(find.text('Cerulean'));
+    await tester.pumpAndSettle();
+    expect(find.text('Selected Segment: cerulean'), findsOneWidget);
+
+    await tester.tap(find.text('Midnight'));
+    await tester.pumpAndSettle();
+    expect(find.text('Selected Segment: midnight'), findsOneWidget);
+
+    // Verify that the first CupertinoSwitch is off.
+    final Finder firstSwitchFinder = find.byType(CupertinoSwitch).first;
+    final CupertinoSwitch firstSwitch = tester.widget<CupertinoSwitch>(firstSwitchFinder);
+    expect(firstSwitch.value, false);
+
+    // Verify that the second CupertinoSwitch is on.
+    final Finder secondSwitchFinder = find.byType(CupertinoSwitch).last;
+    final CupertinoSwitch secondSwitch = tester.widget<CupertinoSwitch>(secondSwitchFinder);
+    expect(secondSwitch.value, true);
+  });
+
   testWidgets('Can change a selected segmented control', (WidgetTester tester) async {
     await tester.pumpWidget(
       const example.SegmentedControlApp(),
@@ -18,4 +51,50 @@ void main() {
 
     expect(find.text('Selected Segment: cerulean'), findsOneWidget);
   });
+
+  testWidgets('Can not select on a disabled segment', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      const example.SegmentedControlApp(),
+    );
+
+    // Toggle on the first CupertinoSwitch to disable the first segment.
+    final Finder firstSwitchFinder = find.byType(CupertinoSwitch).first;
+    await tester.tap(firstSwitchFinder);
+    await tester.pumpAndSettle();
+    final CupertinoSwitch firstSwitch = tester.widget<CupertinoSwitch>(firstSwitchFinder);
+    expect(firstSwitch.value, true);
+
+    // Tap on the second segment then tap back on the first segment.
+    // Verify that the selected segment is still the second segment.
+    await tester.tap(find.text('Viridian'));
+    await tester.pumpAndSettle();
+    expect(find.text('Selected Segment: viridian'), findsOneWidget);
+
+    await tester.tap(find.text('Midnight'));
+    await tester.pumpAndSettle();
+    expect(find.text('Selected Segment: viridian'), findsOneWidget);
+  });
+
+  testWidgets('Can not select on all disabled segments', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      const example.SegmentedControlApp(),
+    );
+
+    // Toggle off the second CupertinoSwitch to disable all segments.
+    final Finder secondSwitchFinder = find.byType(CupertinoSwitch).last;
+    await tester.tap(secondSwitchFinder);
+    await tester.pumpAndSettle();
+    final CupertinoSwitch secondSwitch = tester.widget<CupertinoSwitch>(secondSwitchFinder);
+    expect(secondSwitch.value, false);
+
+    // Tap on the second segment and verify that the selected segment is still the first segment.
+    await tester.tap(find.text('Viridian'));
+    await tester.pumpAndSettle();
+    expect(find.text('Selected Segment: midnight'), findsOneWidget);
+
+    // Tap on the third segment and verify that the selected segment is still the first segment.
+    await tester.tap(find.text('Cerulean'));
+    await tester.pumpAndSettle();
+    expect(find.text('Selected Segment: midnight'), findsOneWidget);
+  });
 }