Support GCP Filestore CSI Driver configuration for Shared VPC in GCloud

What is the nature and description of the request?

We need the CSI driver to be supported and properly tested for Shared VPC. Share VPCs are very common use-case of configuration.

1. The CSI driver is fully GA
   1. https://docs.openshift.com/container-platform/4.14/storage/container_storage_interface/persistent-storage-csi-google-cloud-file.html
2. OCP installation is also fully supported for installation in shared VPC
   1. https://docs.openshift.com/container-platform/4.14/installing/installing_gcp/installing-gcp-user-infra-vpc.html#installing-gcp-user-infra-vpc

It is only nature to expect that if the product is supported for specific configuration, then  all the sub components are also supported for this configuration. If not then this fact should be cleanly stated in the documentation.

Why does the customer need this? (List the business requirements here)

An RXW storage is needed for their workload.

List any affected packages or components.

Google Compute Platform Filestore CSI Driver Operator

Documentation