rolloutRestartTargets by label

**Is your feature request related to a problem? Please describe.**
It would be great if it would be possible to trigger a rollout restart of a deployment, statefulset, etc not only by the name but also by a label. This way if the name is not always the same, a label could be used to specify the targets.

**Describe the solution you'd like**
```
rolloutRestartTargets:
- kind: Deployment
label: app.kubernetes.io/name=traefik
```

Start by tracing how rolloutRestartTargets are parsed and how named Kubernetes targets are resolved. Define the label-based target behavior represented by the Deployment example, and verify that a matching label selects the intended rollout targets without changing name-based behavior.

Written by the indexing model from the issue text.