Feature: Update non `images` fields

[aaaaahaaaaa]

A feature that would be an amazing addition to Keel would be the possibility to update fields in manifests that aren't the image field.

Couple of examples:

• updating labels -> some tools (e.g. Datadog) require specific labels to be set to track versions.
• updating values in CRDs -> e.g. ArgoCD Helm application, where images could be defined as variables in values in the chart.

[HubertBos]

I think you will be better with other tools like ArgoCD based on GIT repos

[aaaaahaaaaa]

@HubertBos ArgoCD is already part of our setup. But ArgoCD's image updater doesn't support the functionality I'm describing here (Flux kinda does). Furthermore, Argo's Image Updater is being completely reworked atm. In my opinion, Argo or Flux are not mutually exclusive with a tool like Keel. I actually think it would make a great combo, Keel becoming essentially a image updater on steroid for those GitOps solutions.