Support multiple network interfaces

[tnozicka]

Pods can have more then one network interface:

• https://cloud.google.com/anthos/clusters/docs/bare-metal/latest/how-to/multi-nic
• https://docs.aws.amazon.com/eks/latest/userguide/pod-multiple-network-interfaces.html

It should be possible to configure ScyllaClusters to use different intefaces / IPs for node-to-node, client-to-node and other traffic.

- [ ] Add design doc for configuring specific network intefaces
- [ ] Add CI support for multiple nics
- [ ] Implementation + tests + docs

[scylla-operator-bot[bot]]

The Scylla Operator project currently lacks enough contributors to adequately respond to all issues.

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• After 30d of inactivity, lifecycle/stale is applied
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You can:

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/lifecycle stale

[tnozicka]

/remove-lifecycle stale /triage accepted