[prometheus-smartctl-exporter] Add ability to include extra labels on PrometheusRule's rules

[achetronic]

Is your feature request related to a problem ?

When deploying this chart in several clusters, having a centralized metrics data lake, and a collector such as Grafana Agent for collecting and pushing the PrometheusRule objects to it, the problem is there is no way in your helm chart to modify the alerts

Describe the solution you'd like.

The idea is to include cluster-related information. It would be super useful to include some labels on the alerting rules for Alertmanager, and even include some extra metrics labels to filter the metrics by cluster

rules:
- alert: SmartCTLDeviceMediaErrors
  expr: smartctl_device_media_errors {my-custom-label="something", another="another-value"} != 0
  annotations:
    message: Device {{ $labels.device }} on instance {{ $labels.instance }} has media errors
  for: 1m
  labels:
    severity: error
    some-label: value
    cluster-name: this-is-a-cluster

Describe alternatives you've considered.

Template and modify directly the PrometheusRule included in your chart and deploy it separatedly, which is not clean enough :)

Additional context.

No response