Allow SBOM file to be specified as previous delivery

Checklist

• documentation is changed or added in ./docs
• unit tests updated to test changes

Description

hoppr/cli/bundle.py

• Add --delivered-sbom-output/-S option. If supplied by user, write the delivered SBOM to the specified location as the last step of hopctl bundle

hoppr/core_plugins/delta_sbom.py

• Move tarfile extraction into new dedicated method _extract_tarfile_bom to reduce cognitive complexity
• If previous delivery is not a tar file, load it as an Sbom if file content has a bomFormat key, otherwise load as a Manifest

test/unit/cli/test_hopctl_bundle.py

• New test module to exercise the above changes

Closes #307 (closed)