genpolicy: support read-only hostPath

[Redent0r]

Merge Checklist

• Followed patch format from upstream recommendation: https://github.com/kata-containers/community/blob/main/CONTRIBUTING.md#patch-format
  • Included a single commit in a given PR - at least unless there are related commits and each makes sense as a change on its own.
• Aware about the PR to be merged using "create a merge commit" rather than "squash and merge" (or similar)
• genPolicy only: Ensured the tool still builds on Windows
• genPolicy only: Updated sample YAMLs' policy annotations, if applicable
• The upstream-missing label (or upstream-not-needed) has been set on the PR.

Summary

Support hostpath pointing to readOnly volume mounts. This scenario was previously blocked by policy due to:
ro != rw

check_mount 2: i options = [\\\"rbind\\\", \\\"rprivate\\\", \\\"ro\\\"]
check_mount 2: p options = [\\\"rbind\\\", \\\"rprivate\\\", \\\"rw\\\"]

Test Methodology

https://dev.azure.com/mariner-org/mariner/_build/results?buildId=550396&view=ms.vss-test-web.build-test-results-tab