Create terraform configuration to provision nodes for a PG HA instance

Should spin up and configure the requisite compute instances and network configuration for a PG HA instance

Requirements

• Provider GCE
• At a minimum, should support a cluster with
  • 3 consul nodes
  • 3 database nodes
  • 1 application node
• Support an arbitrary maximum number of nodes for any component
• Output IP information for created nodes
• Application node(s) ip should be reachable from arbitrary gitlab runners on ports 80 and 443
• Internode communication should be over internal network