Automatically patch desired annotations on STS-provisioned PVCs from the STS spec

[sam-mcbr]

What should the feature do:
Monitor StatefulSet volumeClaimTemplates for any pvc-autoresizer configuration annotations (resize.topolvm.io/storage_limit, resize.topolvm.io/threshold, resize.topolvm.io/inodes-threshold, resize.topolvm.io/increase, resize.topolvm.io/initial-resize-group-by), and patch any existing associated PVCs with these annotations.

What is use case behind this feature:
For existing PVCs created via a StatefulSet volumeClaimTemplate, it is impossible to add annotations to PVC without either deleting it or manually patching the annotations on. This largely defeats the usefulness of the pvc-autoresizer for STS-provisioned PVCs (when running a large number of them) because even if the annotations are applied to the PVCs, any future changes to the values will require further manual deletions/patches.

Our team specifically has a significant number of STS-provisioned PVCs that already exist and it would be a significant amount of work to apply the annotations required to start using the pvc-autoresizer we have deployed. Having this feature built-in to the pvc-autoresizer controller would drastically simplify our adoption and deployment of the project.

Happy to discuss this use-case further and would love to hear your thoughts!

[sam-mcbr]

@llamerada-jp If you all think this would be a nice feature to add, we are happy to work on the PR for it. This is a blocker to us utilizing the pvc-autoresizer we recently deployed so we are happy to pick this up and start work right away 😄