fix: Multiple fixes and introduce end-to-end kind-based test harness

[mmanciop]

• Ensure that k8s.deployment.uid, k8s.cronjob.uid and k8s.namespace.uid (this last one not a standard Otel resource attribute) are sent as resource attributes on the applicable spans
• Embed the source for the telemetry proxy (that is, the bits that are different from the upstream in https://github.com/open-telemetry/opentelemetry-collector-contrib) and build the telemetry-proxy binary locally using the OpenTelemetry collector builder
• Retry on de/instrumenting K8s objects to handle concurrent modification situations

To get to a more healthy setup in terms of how to build the operator inside the Kind tests, the code has been moved around a bit, nesting everything related with the controller under controller/, and adding to the setup a go.work file.