Make bucket name and prefix as part of the S3Connection class

WT-8653 added an S3-hello-world extension. Make changes to create and list objects in a statically configured S3 bucket. The objective is to do the python test changes that are required to:

1. Allow multiple tests on S3 to be run simultaneously from the same user, and from the different user.
2. Make sure failing (or passing) tests do not leave artefacts.
3. Explore and configure retention policies around test objects.

Optional:

1. For debugging, should failing tests leave and preserve artefacts and not the passing tests. If yes when and how would these artefacts be cleared.