Data transfer: extend samples to utilize S3 (minio)

[paullatzelsperger]

WHAT

The MXD walkthrough should be extended so that one provider connector, e.g. "Alice" hosts an asset, that is actually stored in S3 (using the MinIO container image).
Bob then transfers the data into some arbitrary location, e.g. his own S3 store.

In the course of this issue, it should also be tested, whether a transfer HTTP -> S3 can be achieved.

WHY

Highlighting standard Tx-EDC use cases and making them accessible for users of MXD.

HOW

• add terraform resources for MinIO (suggestion: use a kubernetes_deployment)
• create a bucket on provider side and put some test data into that bucket. This needs to be done automatically, without manual commands. (suggestion: could use a job)
• add relevant documentation to mxd/README.md outlining the process, including the correct curl command and transfer request JSON
• repeat for transfers HTTP -> S3
• Suggestion: after each transfer, show the contents of the relevant database tables on provider and consumer side, to further illustrate what's going on.