K8SSAND-1707 ⁃ Add task for rolling restart

[burmanm]

What is missing? At the moment, to do a rolling restart, we must modify the CassandraDatacenter spec. We want a task that would do the same without requiring the modification of Spec.

Why do we need it? As noted in issue https://github.com/k8ssandra/cass-operator/issues/102 we should not be modifying the spec for operations. This is one of operations that should be migrated outside.

Environment

• Cass Operator version:

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  **Anything else we need to know?**:

┆Issue is synchronized with this Jira Task by Unito ┆friendlyId: K8SSAND-1707 ┆priority: Medium