Add multiarch/ARM64 support

[e3b0c442]

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A clear and concise description of what the problem is.

Velero pod with kubevirt-velero-plugin crashes with exec /bin/sh: exec format error when scheduled to an ARM64 node

Describe the solution you'd like:
kubevirt-velero-plugin container built with multi arch support including ARM64

Describe alternatives you've considered:
Restricting velero pods to ARM64 nodes with nodeSelector -- not ideal as we have intentionally scheduled low-impact workloads like the velero controller to our lower-cost ARM64 nodes

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