vmware cloud director multi nic configuration

[4ch3los]

What this PR does / why we need it:
With the machine controller pr kubermatic/machine-controller#1941 it gets possible to deploy nodes with multiple nics. This pr enhances the bootstrap script for static networking, to configure secondary nics aswell.

Which issue(s) this PR fixes:

What type of PR is this?
/kind feature

Special notes for your reviewer:

Does this PR introduce a user-facing change? Then add your Release Note here:

VMware cloud director flatcar nodes will now configure multiple nics, with static networking

Documentation:

TBD

[kubermatic-bot]

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[kubermatic-bot]

Hi @4ch3los. Thanks for your PR.

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