Running EFS CSI in managed cluster (non-EKS)

[hebelsan]

Is your feature request related to a problem? Please describe.
We want to use the efs-csi-driver in a managed Kubernetes cluster that is not EKS.

In a managed control-plane it is preferable to run as many services as possible outside the end-user worker nodes.
However, this is currently not feasible with the EFS CSI driver.

To make the driver compatible with this architecture, two key modifications are required:

1. Configurability for running the driver on either the control plane or worker nodes.
2. Support for passing the region as environment variable.

Describe the solution you'd like in detail
When the driver is set to run in controller mode, the following actions should be bypassed:

• Node server registration,
• Retrieval of instanceID
• Retrieval of availabilityZone

We also want to add support for specifying the region through the AWS_REGION environment variable when the controller is operating in controller mode.

Additional context
We would like to collaborate and contribute this feature if the maintainers agree.
The same feature was added to the aws-ebs-csi-driver with this PR.