For managed nodegroups, propagate labels and taints as tags to ASG

[TiberiuGC]

Description

As a eksctl user, so that I don't manually convert managed nodegroup's labels and taints as tags for ASG, I want them to be converted into tags and propagated automatically. Closes #5575

Manual testing details

Used following config (notice that tags are commented)

managedNodeGroups:
  - name: mng2
    labels:
      my-cool-label: pizza
    taints:
      - key: feaster
        value: "true"
        effect: NoSchedule
    propagateASGTags: true
#    tags:
#      [k8s.io/cluster-autoscaler/node-template/label/my-cool-label](http://k8s.io/cluster-autoscaler/node-template/label/my-cool-label): pizza
#      [k8s.io/cluster-autoscaler/node-template/taint/feaster](http://k8s.io/cluster-autoscaler/node-template/taint/feaster): "true:NoSchedule"

Checking AWS Console for the created ASG for the managed nodegroup, we see the labels and taints being automatically propagated as tags

Checklist

• [x] Added tests that cover your change (if possible)
• [x] Added/modified documentation as required (such as the README.md, or the userdocs directory)
• [x] Manually tested
• [x] Made sure the title of the PR is a good description that can go into the release notes
• [x] (Core team) Added labels for change area (e.g. area/nodegroup) and kind (e.g. kind/improvement)

BONUS POINTS checklist: complete for good vibes and maybe prizes?! :exploding_head:

• [ ] Backfilled missing tests for code in same general area :tada:
• [ ] Refactored something and made the world a better place :star2: