Opentelemetry output support

[pepov]

Currently this produces the following log record on the destination. All the metadata and the original log record are available, although resource attributes are absent. Proper resource attributes will be available once we switch to an opentelemetry input and receive standard otlp logs.

2024-07-05T09:00:23.407Z	info	LogsExporter	{"kind": "exporter", "data_type": "logs", "name": "debug", "resource logs": 1, "log records": 1}
2024-07-05T09:00:23.407Z	info	ResourceLog #0
Resource SchemaURL:
ScopeLogs #0
ScopeLogs SchemaURL:
InstrumentationScope
LogRecord #0
ObservedTimestamp: 2024-07-05 09:00:23.405798 +0000 UTC
Timestamp: 2024-07-05 09:00:23.406049 +0000 UTC
SeverityText:
SeverityNumber: Info2(10)
Body: Str({"ts":"2024-07-05T09:00:22.424670Z","log":"107.147.239.123 - - [05/Jul/2024:09:00:22 +0000] \"POST /index.html HTTP/1.1\" 200 14184 \"-\" \"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3191.0 Safari/537.36\" \"-\"\n","stream":"stdout","time":"2024-07-05T09:00:22.424670292Z","kubernetes":{"pod_name":"log-generator-55867b6d4c-66fdv","namespace_name":"log-generator","pod_id":"682c9ed9-9421-406f-9c7b-cf2b2e62f406","labels":{"app.kubernetes.io/instance":"log-generator","app.kubernetes.io/name":"log-generator","pod-template-hash":"55867b6d4c"},"host":"logging","container_name":"log-generator","docker_id":"dba14a358990c4b6ab82acdf75069952f3b180b3f16dd9527adc7eb11f6d2167","container_hash":"ghcr.io/kube-logging/log-generator@sha256:e26102ef2d28201240fa6825e39efdf90dec0da9fa6b5aea6cf9113c0d3e93aa","container_image":"ghcr.io/kube-logging/log-generator:0.7.0"}})
Trace ID:
Span ID:
Flags: 0
	{"kind": "exporter", "data_type": "logs", "name": "debug"}