Have the `add_cloud_metadata` processor enrich events with EC2 tags

[psypuff]

Describe the enhancement:
Similar to #12263 but not for a specific module, for anything beats is monitoring within an EC2 VM.
Since Jan 2022 EC2 tags are also available through the Instance Metadata Service. This is where the add_cloud_metadata processor fetches metadata from anyway so it doesn't seem like a big change.

Describe a specific use case for the enhancement or feature:
This will allow filtering and grouping hosts based on EC2 tags (e.g. Name) in the Observability metrics inventory view of Kibana (and probably some other views as well). This is much more useable than IPs or instance IDs.

[elasticmachine]

Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane)

[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!

[hatdropper1977]

@cmacknz - Can we get this feature enabled?

[cmacknz]

@bturquet would know if this is planned for the near future.

[bturquet]

Added it in Triage stage for further prioritization, will let you know when we'll have an ETA

[markjandejong]

@bturquet Any word on this feature? This would be extremely useful!

[bturquet]

@dejongm this issue has been added to an internal META issue for the add_cloud_metadata processor, but it is not part of any iteration yet. We may start working on it for may or june iteration only, will share more details when I'll know more, thank you.