Include S3 Gateway Endpoint

[mvandenburgh]

S3 Gateway Endpoints are free of charge and make data transfer to/from S3 from within a VPC free. In the context of Resonant, this could be particularly helpful for EC2 GPU workers that do some kind of data processing and then upload results to S3.

One potential caveat is that you need to have a route table(s) set up in order for the endpoint to work; I'm not sure if that presents any problems for integrating it here.

[brianhelba]

Is the goal of this to reduce costs?

S3 data transfer within an AWS region from S3 to another AWS service (including EC2) is already free.