Brings up four projects:
- one to host the VPC
- two to use the VPC
- one which is outside the VPC
This is based on the diagram in https://cloud.google.com/vpc/docs/shared-vpc and uses the names there where possible for clarity.
On one of the machines, a page is generated demonstrating that the networking is working the way you'd expect. That machine's public IP is output by `terraform apply`.
