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 `///`).

google_maps/lib/main.dart

@@ -47,7 +47,10 @@ class _MyAppState extends State<MyApp> {
         ),
         body: GoogleMap(
           onMapCreated: _onMapCreated,
-          initialCameraPosition: CameraPosition(target: _center, zoom: 11.0),
+          initialCameraPosition: CameraPosition(
+            target: _center,
+            zoom: 11.0,
+          ),
           markers: {
             const Marker(
               markerId: MarkerId('Sydney'),