Allow setting []corev1.EnvVar for our statefull set from the CR

[gtully]

From TZ to JDK_JAVA_OPTIONS there are numerous reasons why a user may wish to augment the environment that the broker has, but currently there is no easy way to do that short of using an init container to manipulate the launch scripts.

Ideally a user should be able to specify, for example:

crd.Spec.Env = []corev1.EnvVar{
{Name: "TZ", Value: "en_IE"},
{Name: "JDK_JAVA_OPTIONS", Value: "-XshowSettings:system"},
}