`containertool` should stream large blobs to and from the registry

[euanh]

containertool currently handles whole files, but all the processes involved (reading, creating the tar archive, gzipping and uploading) can be streamed, reducing resource requirements and latency.

Streaming could be added gradually in different areas:

• copying images from one repository to another - as bytes are received from the source, they are sent to the destination
• uploading resource bundles
• uploading the final application image