feat(node): Add support for Harbor as an on-prem registry (#766)
* Added dir resources/onprem/registry, added Harbor Container Registry icon resources/onprem/registry/harbor.png from https://github.com/cncf/artwork/blob/master/projects/harbor/icon/color/harbor-icon-color.png. Ran convert resize command to resize original. Ran autogen.sh via Docker. Registry.py now exists in diagrams/onprem/ dir. docs/nodes/onprem.md auto-updated.
Co-authored-by: dryhn <dryhn>