* Single attestation when creating VSA
* Create single layer images for referrers attestations
* Move mock to test package. Add artifacts test
* Add test for envelope detection
* Add tests for image/index saving
* Add mirror tests
* Remove AttestationImage field from AttestationManifest
* Update naming. strictReferers != laxReferrers
* Add specific test for SaveReferrers
* Add support for separate attestation storage repo
* Move mapping file types and parsing to config package
* Change signature of Verify to take image/platform
* Separate Attestation Resolvers to their own files (registry, layout and referrers)
* Add support configuring referrers resolution style in mapping.yaml
* Add registry test
