Dart 3.9 / Flutter 3.35 [first LLM release] (#2714)

I got carried away with Gemini and basically rewrote CI and the release
process for the new LLM reality. This work was largely completed by
Gemini.

- Bump all SDK versions to the current beta (3.9.0-0)
- Run `flutter channel beta`
- Wrote `ci_script.dart` to replace the bash scripts
- Converted repository to pub workspace #2499 
- Added llm.md and release.md
- Added redirect for deprecated Samples Index

## Pre-launch Checklist

- [x] I read the [Flutter Style Guide] _recently_, and have followed its
advice.
- [x] I signed the [CLA].
- [x] I read the [Contributors Guide].
- [x] I have added sample code updates to the [changelog].
- [x] I updated/added relevant documentation (doc comments with `///`).

platform_channels/test/src/add_pet_details_test.dart

@@ -38,7 +38,10 @@ void main() {
 
       // Navigate back to /petListScreen
       await tester.pumpAndSettle();
-      expect(router.routeInformationProvider.value.uri.path, '/petListScreen');
+      expect(
+        router.routeInformationProvider.value.uri.path,
+        '/petListScreen',
+      );
     });
   });
 }

platform_channels/test/src/event_channel_demo_test.dart

@@ -34,7 +34,9 @@ void main() {
 
             if (methodCall.method == 'listen') {
               // Emit new sensor values.
-              emitValues(standardMethod.encodeSuccessEnvelope(sensorValues));
+              emitValues(
+                standardMethod.encodeSuccessEnvelope(sensorValues),
+              );
               emitValues(null);
               return standardMethod.encodeSuccessEnvelope(null);
             } else if (methodCall.method == 'cancel') {

platform_channels/test/src/method_channel_demo_test.dart

@@ -23,7 +23,9 @@ void main() {
           return MissingPluginException();
         },
       );
-      await tester.pumpWidget(const MaterialApp(home: MethodChannelDemo()));
+      await tester.pumpWidget(
+        const MaterialApp(home: MethodChannelDemo()),
+      );
 
       // Initially the value of count should be 0.
       expect(find.text('Value of count is 0'), findsOneWidget);

platform_channels/test/src/pet_list_screen_test.dart

@@ -26,7 +26,9 @@ void main() {
     setUpAll(() {
       // Mock for the pet list received from the platform.
       TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
-          .setMockDecodedMessageHandler(basicMessageChannel, (message) async {
+          .setMockDecodedMessageHandler(basicMessageChannel, (
+            message,
+          ) async {
             petListModel = PetListModel.fromJson(message!);
             return null;
           });
@@ -78,7 +80,9 @@ void main() {
 
     testWidgets('BuildPetList test', (tester) async {
       await tester.pumpWidget(
-        MaterialApp(home: Scaffold(body: BuildPetList(petListModel!.petList))),
+        MaterialApp(
+          home: Scaffold(body: BuildPetList(petListModel!.petList)),
+        ),
       );
 
       expect(find.text('Pet type: Dog'), findsOneWidget);

platform_channels/test/src/platform_image_demo_test.dart

@@ -16,11 +16,15 @@ void main() {
           StandardMessageCodec(),
         ),
         (dynamic message) async {
-          var byteData = await rootBundle.load('assets/eat_new_orleans.jpg');
+          var byteData = await rootBundle.load(
+            'assets/eat_new_orleans.jpg',
+          );
           return byteData.buffer.asUint8List();
         },
       );
-      await tester.pumpWidget(const MaterialApp(home: PlatformImageDemo()));
+      await tester.pumpWidget(
+        const MaterialApp(home: PlatformImageDemo()),
+      );
 
       // Initially a PlaceHolder is displayed when imageData is null.
       expect(find.byType(Placeholder), findsOneWidget);