Marketplace VM deployment - allow user to provide a static IP address.

Allow user to enter a static IP address on the Launch Page. This will allow for a more automated setup.

The current approach is that the user must
* fetch the static IP address from External IP Addresses
* add it as an A record to the domain name and
* complete the domain name mapping for the UI and API.

However, if we allow the user to setup the static IP along with entering the domain names for the UI and API as part of the prereqs, then the VM deployment can complete the domain name mapping for the user.

1. static IP address should be optional
2. If the IP address is not provided then the VM deployment should create the static IP address (need to determine if we can complete this step) and use it in the GKE cluster setup.