feat: container scan support for image.tar scan with unspecified image type CN-62

[adrobuta]

Pull Request Submission Checklist

• Follows CONTRIBUTING guidelines
• Includes detailed description of changes
• Contains risk assessment (Low | Medium | High)
• Highlights breaking API changes (if applicable)
• Links to automated tests covering new functionality
• Includes manual testing instructions (if necessary)
• Updates relevant GitBook documentation (PR link: ___)
• Includes product update to be announced in the next stable release notes

What does this PR do?

Adds support for scanning archives without specifying the image type. This implies finding the absolute path of the archive file specified and fallback on different type of extractors when decompressing the archive.

Where should the reviewer start?

How should this be manually tested?

Snyk can directly scan or monitor a Docker or OCI archive by running the following commands:

snyk container test docker-archive:archive.tar
snyk container test oci-archive:archive.tar
snyk container test kaniko-archive:archive.tar

Manually defining the image type adds complexity, increases the risk of errors, and may not account for dynamic updates of the pipelines where the customer has deployed snyk. This change adds support for scanning archives without specifying the image type.

The change can be tested by providing only the .tar filename without specifying docker-archive or oci-archive prefix:
snyk container test archive.tar

What's the product update that needs to be communicated to CLI users?

Adds support for scanning image archives without specifying the image type as prefix.

snyk container test image.tar
snyk container monitor image.tar

[CatalinSnyk]

Approved, but I think a small test would be nice this deserves a test since it's a feat :)

I will be dismissing the review for now, since I think a test should be added or at least explained why no test is required. But I think existing tests can probably be re-used.

[adrobuta]

@PeterSchafer @CatalinSnyk tests were added as part of the plugin upgrade but I've added a test here too for completeness.