feat: add MachineExternalIP to status

[BobyMCbobs]

add MachineExternalIP address to OCIMachine status

What this PR does / why we need it:

when available, writes the public machine IP address to the status along with the private IP address.

Resolves usage with Talos bootstrap+controlplane cluster-api provider.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged): Fixes #379

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