Add Compute backend error metrics to Historical Stats and Real-Time Analytics APIs

apiadded

You can now use the Historical Stats API and the Real-Time Analytics API to troubleshoot backend Compute errors. Sixteen new metrics attribute each backend Compute error to TLS, HTTP, DNS, connection issues, or other sources.

Prior change: Next-Gen WAF: Added detector_scope to simulator signal responses

Following change: Add Notification Service Event Mappings API