[Password Hashing] Interface implementation

[Rundaer]

Hey, I have come accross an issue where on application Users class we had to implement LegacyPasswordAuthenticatedUserInterface which was not mentioned on documentation. Otherwise we were not able to run password migrations.

    legacy:
        algorithm: sha512
    Master\Bundle\CoreBundle\Entity\Users:
        algorithm: sodium
        migrate_from:
            - bcrypt # uses the "bcrypt" hasher with the default options
            - legacy # uses the "legacy" hasher configured above