Multi arch support

[pacostas]

Merge After

• Multi-arch support when downloading and caching assets ForestEckhardt/freezer#12
• go.mod has been updated with the latest version of https://github.com/ForestEckhardt/freezer package.

Summary

This PR does two things:

• Fixes the issue for not finding the /etc/os-release file during the testing
• Adds multi-arch support by introducing two new extra variables, the platform and arch in order to pass them to the freezer go module.

Use Cases

Checklist

• I have viewed, signed, and submitted the Contributor License Agreement.
• I have linked issue(s) that this PR should close using keywords or the Github UI (See docs)
• I have added an integration test, if necessary.
• I have reviewed the styleguide for guidance on my code quality.
• I'm happy with the commit history on this PR (I have rebased/squashed as needed).

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: pacostas / name: Costas Papastathis (957976e)