[Metricbeat] Add AWS S3 Metricset

[kaiyan-sheng]

Amazon S3 CloudWatch Request Metrics: https://docs.aws.amazon.com/AmazonS3/latest/dev/cloudwatch-monitoring.html

Metricbeat Module / Dataset release checklist

This checklist is intended for Devs which create or update a module to make sure modules are consistent.

Modules

For a metricset to go GA, the following criterias should be met:

• Supported versions are documented
• Supported operating systems are documented (if applicable)
• Integration tests exist
• System tests exist
• Automated checks that all fields are documented
• Documentation
• Fields follow ECS and naming conventions
• Dashboards exists (if applicable)
• Kibana Home Tutorial (if applicable)

Metricbeat module

• Example data.json exists and an automated way to generate it exists (go test -data)
• Test environment in Docker exist for integration tests

[exekias]

Can you please link this one and the others to #10115?