Attribute support across telemetry exporters.

[vordimous]

Describe the desired outcome from the user's perspective
As a DevOps engineer, I expect to specify common and custom attributes for my exported logs and metrics. I want the option to configure the value of any system generated attributes

Acceptance criteria

• Attributes defined in a global scope are exported wherever allowed
• Exporter specific attributes can be defined
• Zilla generated attributes have the zilla. prefix
• Zilla generated attributes are also available as ${attribute_name} parameters that can be used in any custom attributes

example schema:

telemetry:
  attributes:
    service.name: ${{ env.OTEL_SERVICE_NAME }}
    service.namespace: ${namespace}
    service.version: ${{ env.ZILLA_VERSION }}
    service.kind: proxy
    another.attribute: my data

  exporters:
    prometheus_metric_exporter:
      type: prometheus
      options:
        attributes:
          prom.binding: prom_ex_${qname}
        endpoints:
          - scheme: http
            path: /metrics
            port: 7190
    otel_exporter_otlp:
      type: otlp
      options:
        attributes:
          otlp.binding: otlp_ex_${qname}
        interval: 5
        signals:
          - logs
        endpoint:
          protocol: http
          location: ${{ env.OTEL_EXPORTER_OTLP_ENDPOINT }}