Fix CRD manifests

[timuthy]

What this PR does / why we need it:
This PR fixes the CRD manifests for several objects that use metav1.ObjectMeta or runtime.RawExtension. It's necessary to set x-kubernetes-preserve-unknown-fields: true for these types because otherwise data underneath related fields is pruned and leads to validation errors in MCM.

Example:

I0824 09:05:30.777736       1 machine_controller_util.go:366] List machines failed on decodeProviderSpecAndSecret: machine codes error: code = [Internal] message = [Error while validating ProviderSpec [spec.disks: Required value: at least one disk is required spec.machineType: Required value: machineType is required spec.region: Required value: region is required spec.zone: Required value: zone is required spec.networkInterfaces.networkInterfaces: Required value: at least one network interface is required spec.scheduling.onHostMaintenance: Unsupported value: "": supported values: "MIGRATE", "TERMINATE" spec.serviceAccounts: Required value: at least one service account is required]]
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I added additional printer columns for Machines that we already use in Gardener along the way (4bb8db0).

Release note:

A bug has been fixed in the pre-delivered CRD manifests for MCM (`/kubernetes/crds`). It caused data to be pruned from MCM related resources and led to reconciliation issues.

[prashanth26]

Thanks for this @timuthy . Love it <3

/invite @AxiomSamarth