Cherry-pick #15097 to 7.x: [Metricbeat] [AWS] Add DynamoDB AWS light module

[ChrsMark]

Cherry-pick of PR #15097 to 7.x branch. Original message:

This PR implements DynamoDB AWS metricbeat Module of #14856

Reference: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/metrics-dimensions.html

Dashboard:

Manual Testing

1. Enable aws module
2. Use the following configuration:

- module: aws
  period: 60s
  metricsets:
    - dynamodb
  credential_profile_name: metricbeat
  regions:
    - eu-central-1

3. Start Metricbeat
4. Check that events are sent to ES or any other output.
   Notes:
5. This requires an AWS account with DynamoDB features
6. In order to automatically populate realistic data in AWS, DM author for instructions.