Include TTL configuration for DynamoDB

We should consider including TTL https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/howitworks-ttl.html configuration to sunset successful ingestions after a specified period to reduce storage costs and improve indexing.

Moved from https://github.com/developmentseed/eoapi-cdk/issues/6 for tracking.

Start with the DynamoDB TTL documentation linked in the issue and trace how successful ingestions are stored in this repository. Define the configurable expiration period and verify that successful records expire as intended while storage costs and indexing behavior improve.

Written by the indexing model from the issue text.