Add support for Machine Preservation

[dergeberl]

How to categorize this PR?

/kind enhancement
/cc @timebertt
/cc @stackitcloud/ske-infrastructure

What this PR does / why we need it:
This PR adds support for the Machine Preservation feature.

gardener PR: gardener/gardener#14767
Other PR for the same feature: gardener/gardener-extension-provider-gcp#1475

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Breaking changes:

[dergeberl]

/hold
The openstack mcm fork does not support this yet.
Fork need to be updated or #195 needs to be merged

[ske-prow]

@dergeberl: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-gardener-extension-provider-stackit-integration-tests	092cfd9	link	true	/test pull-gardener-extension-provider-stackit-integration-tests

Full PR test history. Your PR dashboard. Command help for this repository.
Please help us cut down on flakes by linking this test failure to an open flake report or filing a new flake report if you can't find an existing one. Also see the gardener testing guideline for how to avoid and hunt flakes.

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[ske-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: nschad

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[ske-prow]

LGTM label has been added.

Details

Git tree hash: bfce76fda28b5206126bee89af1e4f0e50417e55

[nschad]

@dergeberl #195 was merged. I think we can unhold this

[dergeberl]

@dergeberl #195 was merged. I think we can unhold this

Lets wait until at least one other provider supports it or gets a review on the PR.