Support for server-side encryption

[plektra]

I would like to have support for encypting any staging files created by dbt. There are multiple supported types of SSE with S3 objects so I guess each of those should be implemented, as they are supported by the API.

The workaround now is to create a new Athena Workgroup, configure it to encrypt all query results and then configure dbt-athena to use this new workgroup.

My honest opinion is that SSE in S3 is designed to be client application's responsibility, so that's why the configuration should be done in dbt-athena. Feel free to have different opinions on this.