Common fields for Orchestrators

[masci]

This is a meta issue to track the work related to defining the common fields for the orchestrator schema.

The output should be a set of required and recommended fields to be added to any event related to containers orchestrators.

[elasticmachine]

Pinging @elastic/integrations-platforms (Team:Platforms)

[masci]

/cc @Alex3k

[kaiyan-sheng]

kubernetes common fields: elastic/beats#23725

[masci]

Orchestrators RFC elastic/ecs#1230

[botelastic]

Hi! We just realized that we haven't looked into this issue in a while. We're sorry! We're labeling this issue as Stale to make it hit our filters and make sure we get back to it as soon as possible. In the meantime, it'd be extremely helpful if you could take a look at it as well and confirm its relevance. A simple comment with a nice emoji will be enough :+1. Thank you for your contribution!