chore: update flutter_web_auth_2 to 4.x

[ChiragAgg5k]

What does this PR do?

Migration guide followed - https://pub.dev/packages/flutter_web_auth_2#upgrading-to-4x

For now we are keeping the old behaviour and disabling usage of webView for linux and windows platforms. But in future we can introduce an option to enable it.

Test Plan

Related PRs and Issues

• 🐛 Bug Report: Appwrite packages still uses flutter_web_auth_2-3.1.2 which uses V1 embedding causing compile errors #1064
• 🚀 Enhancement: flutter_web_auth_2: 3.1.2 is outdated sdk-for-flutter#238
• chore: update flutter_web_auth_2 docs to match 4.x appwrite#9858

Have you read the Contributing Guidelines on issues?

yes.

[rong6767]

As mentioned in the issue, this upgrade will raise the minimum supported iOS version for the Appwrite SDK to iOS 17.4, which I think might be a potential issue for our clients. To work around this limitation, I forked flutter_web_auth_2 and used this3.x-without-v1 branch and made a small modification so I can still use 3.x but don't have any compile errors.

[ChiragAgg5k]

@rong6767 thats great that you have found a workaround for your use case, but we can't use the fork with appwrite 😅
this change will lead to a major bump in the sdk so you can keep on using the older appwrite version, and deal with the warnings by using this approach by Steven - appwrite/sdk-for-flutter#238 (comment)

[DH-555]

Lgtm. The useWebview: false is the correct approach as that's what's required mainly by Apple