Support "referrer-policy" header in "security_defenses" realm section

[jrpedrianes]

Hi,

When I want to configure the "referrer-policy" header option to the "security_defenses" to a realm I can't do that because the provider doesn't manage it:

resource "keycloak_realm" "realm" {
  realm = "Realm Name"

  security_defenses {
    headers {
      referrer_policy = "origin"
    }
  }
}