Removes VSI and all related infra. It has been replaced by [an index
page on
flutter.dev](https://docs.flutter.dev/reference/learning-resources)
Fixes:
#2582#2507
## 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 `///`).
This PR is to include `CarouselView` to M3 demo app.
https://github.com/user-attachments/assets/7db76c06-aa7e-4461-9baa-51fd5c4e6b38
## 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 updated/added relevant documentation (doc comments with `///`).
- [x] All existing and new tests are passing.
---------
Co-authored-by: Eric Windmill <ewindmill@google.com>
