CycloneDX Schemas

syft generates a CycloneDX BOm output. We want to be able to validate the CycloneDX schemas (and dependent schemas) against generated syft output. The best way to do this is with xmllint, however, this tool does not know how to deal with references from HTTP, only the local filesystem. For this reason we've included a copy of all schemas needed to validate syft output, modified to reference local copies of dependent schemas.