Add an option to install the Kubernetes Secrets Store CSI Driver

A new recommended way of accessing secrets from Kubernetes Pods is to use the Kubernetes Secrets Store CSI Driver. This driver allows a Kubernetes workload to access a Google Secret Manager vault (or other enterprise grade secret managers in AWS or Azure).

Using the helm terraform provider, install the Kubernetes Secrets Store CSI Driver as per instructions in their Github project

As we will be using the Google Secret Manager Provider for Secret Store CSI Driver, also install this driver. This driver can be installed implementing the file provider-gcp-plugin.yaml with the kubernetes terraform provider.

The file provider-gcp-plugin.yaml can be transformed to HCL with the Terraform built-in function yamldecode as described in their website:

$ echo 'yamldecode(file("my-manifest-file.yaml"))' | terraform console