[webview_flutter_android] Set support for web authentication

[creatorpiyush]

This PR adds Android support for configuring WebView web authentication behavior through WebSettingsCompat.setWebAuthenticationSupport.

• Added a new Pigeon API for WebSettingsCompat.setWebAuthenticationSupport.
• Implemented the Android host-side proxy in WebSettingsCompatProxyApi.
• Wired the generated Android and Dart Pigeon bindings to expose the new method.
• Updated the Android controller flow to call the new API when the corresponding feature is supported.
• Added/updated constants and example/docs to reflect the new support.
• Added focused tests for the new Android host-side behavior.

working-example.mp4

List which issues are fixed by this PR. You must list at least one issue.
flutter/flutter#186312

Pre-Review Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
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• I signed the CLA.
• The title of the PR starts with the name of the package surrounded by square brackets, e.g. [shared_preferences]
• I linked to at least one issue that this PR fixes in the description above.
• I followed the version and CHANGELOG instructions, using semantic versioning and the repository CHANGELOG style, or I have commented below to indicate which documented exception this PR falls under¹.
• I updated/added any relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or I have commented below to indicate which test exemption this PR falls under¹.
• All existing and new tests are passing.

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[gemini-code-assist]

Code Review

This pull request implements Web Authentication support for the Android WebView, including the necessary Pigeon interface updates, native implementation, and example app integration. Feedback includes addressing a potential compatibility issue with Math.toIntExact on older Android APIs, renaming variables in documentation for clarity, and potentially using an enum to expose all support levels instead of a boolean toggle.

[stuartmorgan-g]

[x] I followed the version and CHANGELOG instructions, using semantic versioning and the repository CHANGELOG style, or I have commented below to indicate which documented exception this PR falls under1.

Thanks for the contribution! You’ve checked boxes in the PR checklist above that are not reflected in this PR, so I’m assuming this is a work in progress and am marking it as a Draft. Please review the checklist, updating the PR as appropriate, and when the state of the PR as posted reflects the checklist please feel free to mark it as ready for review.

[creatorpiyush]

Hello @stuartmorgan-g, PR is up for review; that part was missed to be pushed.

[gemini-code-assist]

Code Review

This pull request introduces support for configuring Web Authentication (WebAuthn) in the AndroidWebViewController via the setWebAuthenticationSupport method. The changes include updates to the Pigeon interface, Android native implementation using WebSettingsCompat, and the Dart API with a new WebAuthenticationSupport enum. A high-severity issue was identified regarding the use of Math.toIntExact, which requires API level 24 and would cause crashes on devices running Android 5.0 to 7.0 (API 21-23) supported by this plugin. Additionally, the WebAuthenticationSupportConstants class should use the @Deprecated annotation instead of just a doc comment for proper IDE and compiler support.

[bparrishMines]

Thanks for the contribution! Added a few comments.

[creatorpiyush]

Hello @camsim99, Please review, rebase done

[creatorpiyush]

Hello,

Due to a setup change and wrong email config a commit was used with wrong email please accept the CLA check
❌ d7a9c6c Author: <piy******and​@nagaroo.com>

[stuartmorgan-g]

Due to a setup change and wrong email config a commit was used with wrong email please accept the CLA check

We cannot accept a PR that has commits that don't correspond to a signed CLA email. If you are the author and the problem is a local configuration error, you need to fix your local configuration, amend the commit, and then re-push with the correct authorship information.