[feature request] Usage with Elastic Common Schema (ECS)

[ebuildy]

Elastic stack provides a specification https://www.elastic.co/guide/en/ecs/current/ecs-reference.html that defines a common set of fields to be used when storing event data in Elasticsearch.

The feature request is about create a formatter to support this schema, for example, the field file is an object https://www.elastic.co/guide/en/ecs/current/ecs-file.html that accepts sub fields path , name etc...

Supporting ECS make easier integration with file-beat and elastic stack .

[reidmorrison]

Great idea. Should be relatively straight forward to create a new formatter using this spec.