add include_users as an alternative to skip_users for authorization

We're using authentication against several ldap DB and we're using the UPN as the username attribute. So it will be easier to configure the role search to include only the users which have a upn corresponding to the domain rather than adding exceptions with skip_users which can become hard to maintain.

Something like:

authz:
  roles_from_adm_corp:
    description: "Authorize on domain1.corp"
    http_enabled: true
    transport_enabled: false
    authorization_backend:
      type: "ldap"
      config:
        hosts:
        - "ldap.domain1.corp:389"
        bind_dn: "CN=elk,OU=Users,DC=domain1,DC=corp"
        password: "xxxxxx"
        rolebase: "dc=domain1,dc=corp"
        rolesearch: "(member={0})"
        rolename: "cn"
        resolve_nested_roles: true
        include_users:
        - "*@domain1.corp" 

Start by locating the LDAP authorization backend configuration and the existing skip_users handling. Confirm how user patterns are matched against the UPN, then implement include_users as the alternative described in the example and add coverage showing that matching users are included while others are excluded.