Add ability to reflect whitelisted labels

[valtaroth]

Following feature request #414 I added the option to have labels mirrored based on two new annotations, <prefix>/reflection-labels and <prefix>/reflection-labels-included.

By default the functionality stays exactly the same with just the content being mirrored. However, once <prefix>/reflection-labels is set to true the source labels will be included in the mirror. <prefix>/reflection-labels-included is a regex list like already used for namespace whitelisting which can be used to finely filter the labels to be mirrored, for example to only mirror labels prefixed with example.com/:

annotations:
  reflector.v1.k8s.emberstack.com/reflection-labels: "true"
  reflector.v1.k8s.emberstack.com/reflection-labels-included: "example\\.com/.*"

[winromulus]

Please also update the documentation (README) and rebase on the latest version

[valtaroth]

Thanks for considering my pull request, I've updated the documentation with my addition and rebased to latest. Please let me know if you require more changes.

[valtaroth]

I rebased again and integrated my changes with the latest refactoring.

[github-actions]

Automatically marked as stale due to no recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[valtaroth]

@winromulus was there anything else you need me to do for this PR or has it been rejected?

[winromulus]

hey @valtaroth I'm currently upgrading the repository a bit and then I'll start the review on this again. There is a similar PR with reflecting source annotations and labels, and I also need to consider a feature flag for this to maintain compatibility (basically a merge of the two PRs with a flag). Currently setting up some automation for this and I'll resume reviews after

[valtaroth]

I understand, thank you for updating me!