Populate container list to allow filtering

[dbaudracco]

This PR fixes the exclusion of containers not working

Background

When using a spinach file like

---
popeye:
  excludes:
    linters:
      deployments:
        instances:
          - codes:
              - 106
            containers:
              - "rx:.*init.*"

I noticed that the relevant containers were not excluded:

· namespace/varnish.................................................................................😱
🐳 init-varnish
😱 [POP-106] No resources requests/limits defined.

After some debugging it appears that this is because the container list is not populated for the appropriate resources: this PR addresses the issue

· namespace/varnish.................................................................................✅

Todo

• proper testing of the resource parsing

[dbaudracco]

If I'm not wrong this supersedes #267, fixes #200 and #168