Retrieve a list of all webhooks configured for the current client account.

Each webhook may be subscribed to one or more event types:

• FNOL (Fnol = 1) — First Notice of Loss: insurance-claim lifecycle for a detected accident.
  Delivered at three notification levels (1 = first detection, 2 = verified, 3 = report-ready).
• Safety Event (EventNotification = 2) — a detected driving safety event (e.g. harsh braking, collision).
  Carries an Event Risk rating from 1 (very low) to 5 (critical).

Deliveries are POST or PUT requests to the configured URL with the envelope:
{ "timestamp": "...", "type": <ManifoldNotificationType>, "data": { ... } }.