Describe the problem you'd like to have solved

To be able to maintain extra login factors, via some of the newly available Management API requests:

• create an authentication method for a given user
• update all authentication methods by replacing them with the given ones

n.b. Similar to this, but for the Management API.

Describe the ideal solution

Would probably be made available on com.auth0.client.mgmt.UsersEntity (similar to #getEnrollments(String))?

Alternatives and current work-arounds

Workaround: can misuse the user import command to set a phone number for SMS factor.