[manila-csi-plugin, cinder-csi-plugin]: Allow cluster-id to be populated from configmap / secret

[1602077]

Follow up from #3069 which got closed when I rebased and I can not reopen now.

What this PR does / why we need it:

Adds supports for loading cluster_id from a secret / configmap in cluster. If clusterID is not set then CLUSTER_NAME can be overridden using extraEnv to pull configuration from an external object.

e.g.

# values.yaml
openstack-cinder-csi:
  clusterID: ""
  secret:
    filename: "cloud-config"
  csi:
    plugin:
      extraEnv:
        - name: CLUSTER_NAME
          valueFrom:
            configMapKeyRef:
              name: cluster-info
              key: cluster_uuid

This allows us to maintain a single configuration for manila / cinder for all of our cluster's, whilst ensuring that they correctly have the cluster-id metadata attached to the created shares / volumes for each cluster.

Which issue this PR fixes(if applicable):
fixes #3070

Special notes for reviewers:
None

Release note:

* [cinder-csi-plugin] Allow cluster-id to be populated from configmap / secret.
* [manila-csi-plugin] Allow cluster-id to be populated from configmap / secret.

[kubernetes-prow]

Hi @1602077. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work.

Regular contributors should join the org to skip this step.

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[kayrus]

/lgtm
/approve

[kubernetes-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kayrus

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