Add Lumberjack output

[andrewkroh]

Add an output that can stream data over the Lumberjack V2 protocol.

Closes #39

[elasticmachine]

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• Start Time: 2022-09-14T05:21:46.076+0000

• Duration: 6 min 34 sec

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[andrewkroh]

Here's an example docker-compose.yml for reference:

version: '2.3'
services:
  barracuda-cloudgen-lumberjack:
    image: docker.elastic.co/observability/stream:local # Requires next release.
    volumes:
      - ./sample_logs:/sample_logs:ro
    environment:
      - STREAM_PROTOCOL=lumberjack
      - STREAM_LUMBERJACK_PARSE_JSON=true
      - STREAM_ADDR=tcp://elastic-agent:5044
      - STREAM_DELAY=5s
      - STREAM_START_SIGNAL=SIGHUP
    command: log /sample_logs/*.log