fix(auth): Add AuthFlowType propagation for the VerifyChallengeAnswer events

[vincetran]

• PR title and description conform to Pull Request guidelines.

Issue #, if available: N/A

Description of changes: This adds AuthFlowType propagation to the VerifyChallengeAnswer events. This was missed because this doesn't really impact the actual authentication functionality but impacts the behind-the-scenes auth flow tracking. Namely, in SignInChallengeCognitoActions when SignInChallengeHelper.evaluateNextStep is called, no AuthFlowType is passed in which means it fallsback to USER_SRP_AUTH.

If USER_AUTH is triggered in SignIn, the ConfirmSignIn API would not have any awareness of it so we check the Amplify configuration.

HOWEVER, this does NOT cover if the user passes in the AuthFlowType into SignIn via AWSCognitoAuthSignInOptions

How did you test these changes? Integration tests passed -- have not done any manual testing yet

Documentation update required?

• No
• Yes (Please include a PR link for the documentation update)

General Checklist

• Added Unit Tests
• Added Integration Tests
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.