[go_router] adds async feature and build context to redirect

[chunhtai]

fixes https://github.com/flutter/flutter/issues/105808 fixes https://github.com/flutter/flutter/issues/99121

Pre-launch Checklist

• [ ] I read the Contributor Guide and followed the process outlined there for submitting PRs.
• [ ] I read the Tree Hygiene wiki page, which explains my responsibilities.
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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 listed at least one issue that this PR fixes in the description above.
• [ ] I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy, or this PR is exempt from version changes.
• [ ] I updated CHANGELOG.md to add a description of the change, following repository CHANGELOG style.
• [ ] I updated/added relevant documentation (doc comments with ///).
• [ ] I added new tests to check the change I am making, or this PR is test-exempt.
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[flutter-dashboard[bot]]

This pull request was opened against a branch other than main. Since Flutter pull requests should not normally be opened against branches other than main, I have changed the base to main. If this was intended, you may modify the base back to go_router_v5. See the Release Process for information about how other branches get updated.

Reviewers: Use caution before merging pull requests to branches other than main, unless this is an intentional hotfix/cherrypick.

[chunhtai]

The ci is failing due to flutter sdk version mismatched, may need some more time to figure out, otherwise the code is ready

[chunhtai]

@loic-sharma PTAL :)