Allow running OpenTelemetry collector

[JamieMagee]

This PR adds the ability to run an OpenTelemetryCollector container image alongside the proxy and updater image. This depends on dependabot/dependabot-core#8210, which adds the OpenTelemetry SDK to dependabot-core.

The main changes in this PR are:

• The OpenTelemetry collector is run after the proxy container, but before the updater container
• 3 new CLI flags:

  • enable-opentelemetry a boolean flag to control if the OpenTelemetry collector container should be created, and the OTEL_ENABLED environment variable should be passed to the updater container

  • collector-image a string flag that controls which container image to use for the OpenTelemetry collector. Defaults to ghcr.io/open-telemetry/opentelemetry-collector-releases/opentelemetry-collector-contrib:latest. See the Dockerfile for this container image here

  • collector-config a string flag that sets a path to OpenTelemetry collector YAML configuration. I've been using the following for testing:

    Click to expand

    receivers:
      otlp:
        protocols:
          grpc:
    
    exporters:
      debug:
    
    processors:
      batch:
    
    service:
      pipelines:
        traces:
          receivers: [otlp]
          processors: [batch]
          exporters: [debug]
        metrics:
          receivers: [otlp]
          processors: [batch]
          exporters: [debug]

[jpinz]

Just some questions/comments.

[jakecoffman]

Some of this might change if we decide on a different architecture so let's hold off merging this until then.