Alerts and webhooks endpoints missing `/system` prefix

[david-crespo]

They have a system/alerts tag and as far as I know the resources are fleet-scoped, so we will probably want to add the prefix. API versioning should make it not too a big deal for clients.

omicron/nexus/external-api/output/nexus_tags.txt

Lines 183 to 200 in 229ae4c

	API operations found with tag "system/alerts"
	OPERATION ID METHOD URL PATH
	alert_class_list GET /v1/alert-classes
	alert_delivery_list GET /v1/alert-receivers/{receiver}/deliveries
	alert_delivery_resend POST /v1/alerts/{alert_id}/resend
	alert_list GET /v1/alerts
	alert_receiver_delete DELETE /v1/alert-receivers/{receiver}
	alert_receiver_list GET /v1/alert-receivers
	alert_receiver_probe POST /v1/alert-receivers/{receiver}/probe
	alert_receiver_subscription_add POST /v1/alert-receivers/{receiver}/subscriptions
	alert_receiver_subscription_remove DELETE /v1/alert-receivers/{receiver}/subscriptions/{subscription}
	alert_receiver_view GET /v1/alert-receivers/{receiver}
	alert_view GET /v1/alerts/{alert_id}
	webhook_receiver_create POST /v1/webhook-receivers
	webhook_receiver_update PUT /v1/webhook-receivers/{receiver}
	webhook_secrets_add POST /v1/webhook-secrets
	webhook_secrets_delete DELETE /v1/webhook-secrets/{secret_id}
	webhook_secrets_list GET /v1/webhook-secrets

[hawkw]

I feel like you and I may have had a conversation about whether or not they ought to be under /system at the time, but it is also possible I may have made that up. I would be open to adding that, especially given that it's versioned.