container test doesn't support --diff

[mattwynne]

Is your feature request related to a problem? Please describe.

We were surprised that the fossa sbom test command supports --diff but the fossa container test does not.

[github-actions]

Thank you @mattwynne for creating this issue. If this is in regards to a defect, product question or feature request: you should use our support portal at https://support.fossa.com to file a request, as you would receive more immediate support.