Ensure default encryption is enabled for AWS EBS Volumes

Unencrypted AWS EBS Volumes may expose sensitive customer data.

In AWS Console -

1. Sign in to AWS Console and go to the Amazon EC2 console.
2. Select the region from the navigation bar.
3. Select EC2 Dashboard from the navigation pane.
4. In the upper-right corner of the page, select Account Attributes, EBS encryption.
5. Select Manage.
6. For Default encryption key, select a symmetric customer managed key.
7. Select Update EBS encryption.

In terraform -

1. Create an aws_ebs_encryption_by_default resource, and set 'enabled' to 'true'.

References:
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSEncryption.html
https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/ebs_encryption_by_default