[Tracking] Add tracing capabilities

[thisthat]

Goal

Instrument the Keptn Lifecycle Operator 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.

Each component should have its own tracer:

• Scheduler: keptn/scheduler
• Webhook: keptn/webhook
• Workload: keptn/operator/workload
• WorkloadInstance: keptn/operator/workloadinstance
• Task: keptn/operator/task
• TaskInstance: keptn/operator/taskinstance

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

The webhook is the one that always starts a trace.
The scheduler should create a Client Span for each reconciliation.

DoD

• The Lifecycle Controller generates the aforementioned spans as part of a single trace

Resources

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

List

• Add tracing capability for Scheduler #96
• Add tracing capability for Webhook #98
• Add tracing capability for Workload #99
• Add tracing capability for WorkloadInstance #100
• Add tracing capability for Task #101
• Report traces to Jaeger #132
• Adapt documentation to add OTel Collector installation as pre-requisite #133