Add option to define an existing Lan to IONOSCloudMachine

[arteonprifti]

Describe the solution you'd like:
When specifying a failoverIP it will create the failover group in the same LAN where all the other nodes are created, including those not part of the failover group.
This is not optimal for the following cases:

• an existing failover group in a separate LAN cannot be migrated without disruption
• creating failover groups in a separate LANs is required

For that reason I propose to add a new option called failoveIPLanID, which accepts an existing LAN ID in the VDC and it is not considered when not set.