feat: Add InternalIPs to CreateMachineResponse

[jamand]

How to categorize this PR?

/kind enhancement

What this PR does / why we need it:

Similar to gardener/machine-controller-manager-provider-openstack#322
Server InternalIPs are now returned on created Machines, so that they may be used for access. This is needed, as the provided hostname field already written into is the Machine Status.Addresses is not resolvable on STACKIT.

Which issue(s) this PR fixes:
x

Special notes for your reviewer:

The client Suite was previously not registered and there was a small bug in one test case.

/hold Running tests first

[ske-prow]

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[jamand]

@breuerfelix Thanks!

I also ran a test in an ondemand environment testing the self-hosted shoot scenario using gardenadm (only in this case the IP is written into the Status field. I could verify that the Addresses field now has an additional entry with the server internal IP (Type: InternalIP) next to the already previously created Hostname entry.

[jamand]

/unhold