chore(auth): Migrate TOTP setup to use case classes

[mattcreaser]

• PR title and description conform to Pull Request guidelines.

Issue #, if available:

Description of changes:

• Moves the TOTP Setup functions into use case classes.
• Fixes some bugs in setupTotp where Amplify would hang (never invoke callbacks) in certain scenarios.

How did you test these changes?

• Unit test

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.

[tylerjroach]

I've noticed this error will never surface anymore:

CognitoAuthExceptionConverter.lookup(
  error,
  "Cannot find a multi-factor authentication (MFA) method."
)

This looks like it was just a generic catch all but want to make sure the change is expected.

[mattcreaser]

The string there is the message set on unmapped exception types (i.e. if we return an UnknownException). It was indeed intentionally omitted since we map exceptions at the top level now, which is much simpler, although it does cause a loss of context. I also thought the message didn't make any sense given what the user is trying to do.

If we wanted to retain the contextual message we can do something like:

internal inline fun <R> mapExceptions(fallbackMessage: String, block: () -> R): R {
    try {
        return block()
    } catch (e: Exception) {
        throw CognitoAuthExceptionConverter.lookup(e, fallbackMessage)
    }
}

and then execute becomes:

suspend fun execute(): TOTPSetupDetails = mapExceptions("Cannot setup TOTP") {
  // ....
}

[tylerjroach]

Thanks for clarification. I am ok with original change.

The base branch was changed.