NewDefaultMetadataRestorer returns an instance of the DefaultMetadataRestorer struct.

NewSHAStore returns a new SHAStore for mapping buildpack IDs to layer names and their SHAs.

MetadataRestorer given a group of buildpacks and metadata from the previous image and cache, will create `<layers>/<buildpack-id>/<layer>.toml` files containing `metadata` that the buildpack previously wrote.

SBOMRestorer handles the restoration of SBOM layer data.