Migrate engine started and stopped to telemetry events

[jfallows]

Engine outputs the zilla.yaml configuration, started event, exceptions, and stopping / stopped event directly to stdout.

However, the started and stopped events are helpful for monitoring behavior and detecting misconfigured zilla instances.

Migrate started and stopped events from stdout to telemetry and provide a convenient way to enable stdout exporter from zilla start instead of requiring it in zilla.yaml.

Only one instance of stdout is needed to get the benefit, so stdout exporter can be updated to be no-op for subsequent instances. This will prevent log messages being written multiple times to stdout.

Once this task is completed, the engine started and stopped events should also successfully export via otlp.