Ensure flow logs are enabled for AWS Global Accelerator

AWS Global Accelerator has flow logging disabled. This may make audit challenging.

In AWS Console -

1. Create an Amazon S3 bucket for your flow logs in your AWS account.
2. Add the required IAM policy for the AWS user who is enabling the flow logs.
3. Run the following AWS CLI command: 'aws globalaccelerator update-accelerator-attributes' with the '--flow-logs-enabled' flag to enable flow logs.

In Terraform -

1. In the aws_globalaccelerator_accelerator resource, set the flow_logs_enabled field to true.

References:
https://docs.aws.amazon.com/global-accelerator/latest/dg/monitoring-global-accelerator.flow-logs.html
https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/globalaccelerator_accelerator#flow_logs_enabled