-`region` (String) Region to retrieve the image for. Only required for AWS.
The Constellation OS image must be [replicated to the region](https://docs.edgeless.systems/constellation/workflows/config),and the region must [support AMD SEV-SNP](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/snp-requirements.html), if it is used for Attestation.
-`reference` (String) CSP-specific unique reference to the image. The format differs per CSP.
-`short_path` (String) CSP-agnostic short path to the image. The format is `vX.Y.Z` for release images and `ref/$GIT_REF/stream/$STREAM/$SEMANTIC_VERSION` for pre-release images.
-`$GIT_REF` is the git reference (i.e. branch name) the image was built on, e.g. `main`.
-`$STREAM` is the stream the image was built on, e.g. `nightly`.
-`$SEMANTIC_VERSION` is the semantic version of the image, e.g. `vX.Y.Z` or `vX.Y.Z-pre...`.
-`version` (String) Semantic version of the image.