Implement basic support for Otel

[pdabelf5]

Add equivalent support for OpenTelemetry as was deprecated for OpenTracing with a similar UX.

apiVersion: v1
kind: ConfigMap
metadata:
  name: nginx-config
data:
  otel-exporter-endpoint: "[(http|https)://]host:port" # Required
  otel-exporter-trusted-certificate-secret: # Optional nginx.org/ca Secret name 
  otel-exporter-header-name: "name" # Optional
  otel-exporter-header-value: "value" # Optional
  otel-service-name: "unknown_service:nginx" # Optional
  otel-global-trace-enabled: "false" # Optional, enables otel tracing at the http context

Support at the Server/Location level will be via snippet on VS/VSR/Ingress