feat: create GrafanaDashboard CR for GrafanaOperator

[jkleinlercher]

Closes #220

📑 Description

User who have the grafana-operator deployed get automatically the K8sGPT Grafana Dashboard.

✅ Checks

• [ ] My pull request adheres to the code style of this project
• [ ] My code requires changes to the documentation
• [ ] I have updated the documentation as required
• [ ] All the tests have passed

ℹ Additional Information

[JuHyung-Son]

after i installed grafana operator. i confirmed GrafanaDashboard is created and k8sgpt-overview cm is correctly injected. i haven't used grafana operator, but it seems works well.

┌───────────────────────────────────────────────────────────────────────────────────────────────── Grafanadashboards(all)[1] ──────────────────────────────────────────────────────────────────────────────────────────────────┐
│ NAMESPACE↑                                NAME                                           NO MATCHING INSTANCES                               LAST RESYNC                               AGE                                   │
│ default                                   k8sgpt-overview                                true                                                2m26s↑                                    2m26s                                 │