CL-627 | Add DynamoDBBackup module

[gsoria]

This PR adds a new module to handle DynamoDB backups.

Testing steps

• Create dynamodb table and a backup:

# create a table
aws dynamodb create-table \
    --table-name Music \
    --attribute-definitions \
        AttributeName=Artist,AttributeType=S \
        AttributeName=SongTitle,AttributeType=S \
    --key-schema \
        AttributeName=Artist,KeyType=HASH \
        AttributeName=SongTitle,KeyType=RANGE \
    --provisioned-throughput \
        ReadCapacityUnits=5,WriteCapacityUnits=5 \
    --table-class STANDARD

# Create backup
aws dynamodb create-backup --table-name Music --backup-name Music_backup

• Run aws-nuke including DynamoDBBackup module
• Verify if resources were cleaned up successfully

# List backups
aws dynamodb list-backups

[swhite-oreilly]

Confirmed deletion of the backup successfully deleted here.