Develop capability to copy images to and from a directory on the filesystem

[whatsacomputertho]

Overview

We are working on the ability to copy images between two registries while maintaining digest integrity

• Develop capability to copy images between registries and maintain digest integrity #12

That effectively would serve as a python-native implementation of

# Copy from registry to registry
skopeo copy docker://$SRC_IMAGE docker://$DEST_IMAGE

This issue will focus on a similar capability, this time a python-native implementation of

# Copy from registry to directory
skopeo copy docker://$SRC_IMAGE dir:$DEST_DIR

# Copy from directory to registry
skopeo copy dir:$SRC_DIR docker://$DEST_IMAGE

Acceptance

• It is possible to copy an image from a registry to a directory using containerimage-py
• It is possibly to copy an image from a directory to a registry using containerimage-py
• The usage of these new capabilities are documented
• Example scripts are written for these new capabilities
• There is unit test coverage for these new capabilities