Make s3_output explicit

[gwionap]

• Updating s3_output in _create_temp_database
• Add new region environment variable AWS_ATHENA_QUERY_REGION

[gwionap]

@Thomas-Hirsch - above is needed so that _create_temp_database uses the same s3 output location as used elsewhere and for it not to default to the workgroup's location.

Also, I think an additional environment variable is needed for grabbing the default region when used with dbtools and where AWS_DEFAULT_REGION and AWS_REGION are fixed by your environment / outside your control. I've used APP_AWS_REGION for now, but open to suggestions for a better name.

[gwionap]

@Thomas-Hirsch - changes made and tested ready for final review.