Enable to declare AttachIDs, WithShared and WithLocal in config file

[af12066]

Description

We have made it possible to declare attachIDs, withShared and/or withLocal for security groups in cluster.yaml

e.g.

apiVersion: eksctl.io/v1alpha4
kind: ClusterConfig

nodeGroups:
  - name: nodegroup1
    securityGroups:
      attachIDs:
        - sg-abcd1234
        - sg-567890ef
    ...

cf. #460

Checklist

• Code compiles correctly (i.e make build)
• Added tests that cover your change (if possible)
• All tests passing (i.e. make test)
• Added/modified documentation as required (such as the README)
• Added yourself to the humans.txt file

[errordeveloper]

Thanks! Clearly something that was overlooked in review :)