chore(example): added WASM support to example

[JaffaKetchup]

Supersedes #1867 by @josxha.

• Reset web index.html config file to initial state in Flutter 3.22
• Also adds required headers to Firebase config (hopefully)

Would like to add an indicator using dart-lang/sdk/issues/55694 when it becomes available, to confirm usage of WASM.

[josxha]

Also adds required headers to Firebase config (hopefully)

It's possible to deploy branches temporarily on firebase hosting, see https://github.com/FirebaseExtended/action-hosting-deploy?tab=readme-ov-file#channelid-string.
Maybe a good way to test those changes or even to setup a permanent hosted version running on wasm?

[JaffaKetchup]

It's possible to deploy branches temporarily on firebase hosting, see FirebaseExtended/action-hosting-deploy#channelid-string.

Yep, I've looked into this extensively before. However, I disabled it, as most of our PRs come from forks, and for security reasons, GitHub Actions and Firebase won't do this from a fork PR. I can try deploying a preview version manually perhaps?

[JaffaKetchup]

https://fleaflet-firebase--preview-wasm-bfczu5tt.web.app/

Can confirm it doesn't work, but only because the CTP uses Dio which doesn't support Dio yet. Not sure why I couldn't reproduce this locally, but I guess we'll have to hold off for now.

[josxha]

Open pull request here:

• Adapt dart2wasm cfug/dio#2215

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While I tested my branch I had the problem that the polygon stresstest page gets stuck and doesn't seem to unfreezed after i zoomed in. Does this happen here too?

[JaffaKetchup]

Waiting for:

• Adapt dart2wasm cfug/dio#2215
• A Flutter release (beta channel) with Dart 3.5.0-185.0.dev, to include dart-lang/sdk@6b71aa1