FR (Authenticator): Override function support for ChangePassword

### On which framework/platform would you like to see this feature implemented?

Vue

### Which UI component is this feature-request for?

Authenticator

### Please describe your feature-request in detail.

Currently, the Authenticator component supports override functions for the following actions:[1]

1. Auth.signUp | handleSignUp
2. Auth.signIn | handleSignIn
3. Auth.confirmSignIn | handleConfirmSignIn
4. Auth.confirmSignUp | handleConfirmSignUp
5. Auth.forgotPassword | handleForgotPassword
6. Auth.forgotPasswordSubmit | handleForgotPasswordSubmit

However, it is missing support for other auth events such as `changePassword`. In our specific case, this has made it challenging to streamline the login experience between a returning user (no change password requirement) and a brand new user logging in for the first time (one who must first statisfy the `NEW_PASSWORD_REQUIRED` challenge). I believe being able to simply receive the ChangePassword auth event in the same way we can receive the SignIn auth event would allow us to centralize the app entry logic universally.

[1: Authenticator customization docs](https://ui.docs.amplify.aws/react/connected-components/authenticator/customization#override-function-calls)

### Please describe a solution you'd like.

No specific implementation preferences; just want to be able to override the changePassword event with the Authenticator component.

(Not sure if duplicate of [issue 3418](https://github.com/aws-amplify/amplify-ui/issues/3418), please close if so)

### We love contributors! Is this something you'd be interested in working on?

- [X] 👋 I may be able to implement this feature request.
- [ ] ⚠️ This feature might incur a breaking change.

Start with the Vue Authenticator component and the Authenticator customization documentation linked in the issue, comparing the listed override functions with the missing changePassword event. Review issue 3418 for possible overlap; done means the ChangePassword flow supports an override consistently with the existing auth actions.

Written by the indexing model from the issue text.