IdM and AD users are identified by Kerberos Principal name and Email address interchangeably

Issue

• Network users (IdM and AD) are identified by both Kerberos Principal name and Email address, and they can authentication with either identifier.

  # ipa user-show bob
    User login: bob
    First name: Bob
    Last name: User
    Home directory: /home/bob
    Login shell: /bin/sh
    Principal name: bob@EXAMPLE.COM
    Principal alias: bob@EXAMPLE.COM
    Email address: info@email.example.com
    UID: 510600003
    GID: 510600003
    Account disabled: False
    Password: False
    Member of groups: ipausers
    Kerberos keys available: False
  
  # id bob@EXAMPLE.COM
  uid=510600003(bob) gid=510600003(bob) groups=510600003(bob)
  
  # id info@email.example.com
  uid=510600003(bob) gid=510600003(bob) groups=510600003(bob)