[Feature] Support for anti-affinity/affinity rules for the created machines

[geetikabatra]

/kind feature

Openstack supports defining anti-affinity / affinity rules for VMs. This feature adds support for the user to specify affinity/anti-affinity grouping for the VMs.

Use case: The user created 3 Machine object and want all 3 VMs to run on different hosts to improve resiliency from host failures. This can easily be realized by creating the anti-affinity rule for the 3 VMs

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