`kctrl`: Better errors for malformed `package-resources.yml`

**Describe the problem/challenge you have**
[A description of the current challenge that you are experiencing.]
Today, if resources are missing from `package-resources.yml` we get an error somewhat like this,
```bash
$ kctrl package release --version 1.0.0
kctrl: Error: Parsing resource config 'package-resources.yml':
Unknown apiVersion '' or kind '' for resource
```

**Describe the solution you'd like**
[A clear and concise description of what you want to happen. If applicable a visual representation of the UX.]
We should have a better error message or even ignore the cases in which a resource is not necessary.

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Start by reproducing `kctrl package release --version 1.0.0` with the malformed or incomplete `package-resources.yml`, then trace the package resource parsing path. Done means the command reports a clearer, actionable error for missing resources, or consistently ignores resources that are not needed.

Written by the indexing model from the issue text.