[grafana] feat: adds multi-org support to sidecar dashboards

[VeseliD]

Converts sidecar.dashboards.provider to a list at
sidecar.dashboards.providers allowing the definition of multiple
providers that can be mappped to orgs as required.

Still supports the singular variant to retain backwards compatibility
and will prepend it to any configured providers

Results in multi-org support defining providers like the example below which

sidecar:
    folderAnnotation: grafana_folder
    dashboards:
      enabled: true
      providers:
        - name: prod
          orgid: 1
        - name: nonprod
          orgid: 2
        - name: ops
          orgid: 3

This then allows dashboard configmaps to be define the annotation grafana_folder: /tmp/dashboards/ops instructing the sidecar to put the dashboard in the folder that's been specific in our configuration above.

apiVersion: v1
kind: ConfigMap
metadata:
  name: my-dashboard
  namespace: monitoring
  labels:
    grafana_dashboard: '1'
  annotations:
    grafana_folder: /tmp/dashboards/ops/
data:
  my-dashboard.json: |-
   {}

Please, have in mind that you can define your own folderAnnotation:
We used value grafana_folder just as example.

We reference to this PR: #2939

[CLAassistant]

All committers have signed the CLA.

[VeseliD]

Hello team, any update on this PR?
Thanks!

[zanhsieh]

@jkroepke @Xtigyro Can you review this PR please?

[jkroepke]

I have that feeling, that the current implementation is too complex for normal end-users.

While the provisioning part looks good, using an annotation like grafana_folder and require with value like /tmp/dashboards/ops/ into it where ops stands for orgID 3, it feels not great.

What happens, if /tmp/dashboards/ops2/ is used? An error will be not reported. to end-users.

Too much glue is used here to archive something.

However, I will be not the part, who is blocking this.