Add vSphere CCM

[maxilampert]

What this PR does / why we need it:
Adds vShpere external ccm controller.
Example kubeone config used for testing. Tested with current version of vCenter and ESXI 7.

apiVersion: kubeone.io/v1beta1
kind: KubeOneCluster
versions:
  kubernetes: '1.19.3'
cloudProvider:
  vsphere: {}
  external: true
  cloudConfig: |+
    global:
      port: 443
      # set insecureFlag to true if the vCenter uses a self-signed cert
      insecureFlag: true
      # settings for using k8s secret
      secretName: vsphere-ccm-credentials
      secretNamespace: kube-system
    # vcenter section
    vcenter:
      tenant-techrowdy:
        server: vcsa.example.com
        datacenters:
          - DC

Which issue(s) this PR fixes:
Implements #616 for vSphere controller
Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[kubermatic-bot]

@maxilampert: Adding the "do-not-merge/release-note-label-needed" label because no release-note block was detected, please follow our release note process to remove it.

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[kubermatic-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: maxilampert
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• c229328 Add vSphere CCM

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[kubermatic-bot]

Hi @maxilampert. Thanks for your PR.

I'm waiting for a kubermatic member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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