Use S3 inventory to simplify the batching process

[austinbyers]

Instead of iterating over the entire S3 bucket, you can configure an S3 inventory which saves copies of the bucket contents.

Unfortunately, this is not yet supported by Terraform: hashicorp/terraform-provider-aws#532

This might still be worth implementing manually to avoid the need for a batching function

[austinbyers]

Closing as "wontfix" for the following reasons:

• No terraform support
• It could still take 5+ minutes to enqueue millions of items from inventory into SQS, so having a batcher Lambda would likely still be necessary
• Inventory could be delayed by a day whereas the current implementation guarantees that your retroactive analysis is valid as of the time the command is executed