add Trivy and "docker scan" (aka

[simonsdave]

Struggling to get Clair to work effectively.
Other docker image vulnerability assessment tools exist.

• Trivy
• Snyk (via docker scan)

Given the above let's morph clair-cicd to have non-clair options.

Some potentially useful references

• docker: Best practices for scanning images
• 26 May '21 - How to Use Docker Scan to Find Vulnerabilities in Your Images