Support delete all authentication methods endpoint

[jimmyjames]

Changes

Adds new method deleteAllAuthenticationMethods(String userId) to the UsersEntity to delete all authenticators for the given user.

References

Calls the delete all authenticators endpoint

Testing

• [X] This change adds test coverage
• [X] This change has been tested on the latest version of the platform/language or why not

Checklist

• [x] I have read the Auth0 general contribution guidelines
• [x] I have read the Auth0 Code of Conduct
• [x] All existing and new tests complete without errors