Collect component stdout logs with a filelog receiver

[krisztianfekete]

Every ate component writes structured JSON logs to stdout: ateapi, atelet, atecontroller, atenet, ateom, podcertcontroller. Today kubectl logs is the only way to read them, so there's no way to search across components or across time.

Came out of the discussion on #1683.

What we need

• An optional filelog receiver over /var/log/pods in the kind manifests.
• That means a DaemonSet collector. The current one is a Deployment with no hostPath.
• k8sattributes on the logs pipeline, so records get pod and node. Associate on k8s.pod.uid from the path.

Gotchas

• Set severity parsing explicitly.
• trace_id, span_id and trace_flags are already top level lowercase hex, so trace_parser maps them with no extra work.
• ateom wraps actor output with the ate.* keys in a nested group, and the key name differs by environment: labels on kind, logging.googleapis.com/labels on GKE. Handle both or we silently lose every actor on one of them.
• ateapi also sends its two lifecycle events over OTLP ((feat): Actor lifecycle events over otlp #1658), so those would arrive twice. Either leave ate-system out of the include globs, or drop records whose scope is github.com/agent-substrate/substrate/internal/actorevent.

cc Jeff Luo (@JeffLuoo)