Function validate_incoming_session_pix_config 

pub fn validate_incoming_session_pix_config(
    cfg: &IncomingSessionPixConfig,
    max_session_packet_rate: u64,
) -> Result<()>

Validates the incoming-PIX invariants that span quota, supervision and memory settings.

max_session_packet_rate is the fastest a Session is assumed to go. Without fill it bounds max_recovery_time directly; with fill it caps the fill.max_rate the deadline may count on.