Update WASM page with info from Feb 2024 release

[kevmoo]

Page URL

https://docs.flutter.dev/platform-integration/web/wasm

Page source

No response

Describe the problem

Should mention the new js_interop and pkg:web work and how that's needed to allow Flutter web apps to compile to Wasm

Should also mention that the feature will be available (soon) on the Flutter beta channel

Expected fix

No response

Additional context

No response

I would like to fix this problem.

• [ ] I will try and fix this problem on docs.flutter.dev.