Add tracing capability for Workload

[thisthat]

Goal

Instrument the WorkLoad controller with the OTel SDK to export traces.

Technical Details

Use OTel Go to manually instrument the code to export the following spans as a single trace:

The Trace Context should be propagated into the CRDs via a common metadata field TraceContext. The context will be propagated using this immutable map.

The Workload controller shall use keptn/operator/workload as the component name.
The Workload controller shall extract the parent Span from TraceContext.
Each Span should be created with the following OTel Attribute:

• KeptnApp as keptn.deployment.app_name
• KeptnWorkload as keptn.deployment.workload
• KeptnVersion as keptn.deployment.version

Acceptance Criteria

• Workload creates a Consumer Span when it starts to handle a Workload CRD
• Workload creates a Producer Span when it creates a WorkloadInstance
• Attributes with Keptn information should always be added whenever possible (e.g. AppName, status of the task)

DoD

• The Workload Controller generates Spans

Resources

• https://github.com/open-telemetry/opentelemetry-go/tree/main/example