Sidecar monitor for stuck downloader, and kills python when detected

[bjorn-amd]

Description

Model cache sidecar now detects when nothing has been downloaded for five minutes and then kills the downloader so that it can retry the download.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist:

• My code follows the style guidelines of this project. See contributing-guidelines.md
• Existing workload examples run to completion after my changes (if applicable)
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[AVSuni]

LGTM 🙏