feat: set trivy --platform dynamically

[giacomolanciano]

Description

Add support for scenarios where scanned objects rely on images having only non-amd64 architecture variants (e.g. arm64). The operator now infers the architecture and sets trivy's --platform arg accordingly.

Related issues

• Vulnerability scanner unable to scan arm64-only images #1469
• Trivy failed to scan linux/arm64 only image trivy#5279

Checklist

• I've read the guidelines for contributing to this repository.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).

[CLAassistant]

All committers have signed the CLA.

[afdesk]

@giacomolanciano thanks for your contribution!
it's a really interesting feature here
we'll take a look

[giacomolanciano]

@afdesk thank you, glad to hear that!

I saw the CI was failing, should be fixed now. Please let me know if I can help in any way.