management-api TLS connection and certs

[burmanm]

What is missing?
cass-operator deployment needs the management-api certs mounted if it wants to connect to the cassandra pods, in the case of removing the requirement for external secrets.

This requires all the maintained CassandraDatacenter certs to be in the cass-operator pod. And we need to maintain the lifecycle to restart the cass-operator, if any new ones are created or older modified etc. This is a bit beyond cass-operator's own functions, but documented here for the external secrets issue in k8ssandra/k8ssandra-operator#598 as it impacts how cass-operator works.

Why do we need it?
Otherwise we can't connect to cassandra pods that are using secure communication.

Environment

• Cass Operator version:

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

┆Issue is synchronized with this Jira Story by Unito
┆Issue Number: CASS-28