[controller] Add NFSStorageClass controller and validation webhook for StorageClasses with provisioner nfs.csi.k8s.io

[AleksZimin]

Description

This PR introduces the NFSStorageClass controller along with a validation webhook for StorageClasses that utilize the nfs.csi.k8s.io provisioner. The new controller is responsible for managing NFS-based StorageClasses, ensuring streamlined lifecycle management. The accompanying validation webhook is designed to enforce strict control over these StorageClasses, prohibiting any direct modifications, creations, or deletions. All changes to NFS StorageClasses must be made through the NFSStorageClass resource, ensuring compliance with defined standards and configurations.

Why do we need it, and what problem does it solve?

• Controlled Management: The NFSStorageClass controller automates the management of NFS-based StorageClasses, ensuring that they are handled consistently. This automation simplifies the setup and ongoing management for users, providing a straightforward mechanism to manage NFS storage configurations without needing to handle complex manual processes.
• Strict Validation: The validation webhook prevents unauthorized or accidental changes to NFS-based StorageClasses, enforcing that all modifications are made through the designated NFSStorageClass resource. This helps maintain system integrity and prevent configuration drift, while also simplifying compliance by funneling all changes through a controlled process.

What is the expected result?

• A robust management system for NFS-based StorageClasses that centralizes control and enforces configuration standards.
• Prevention of direct modifications to NFS StorageClasses, ensuring that all changes are vetted and managed through the NFSStorageClass resource.

Checklist

• The code is covered by unit tests.
• e2e tests passed.
• Documentation updated according to the changes.
• Changes were tested in the Kubernetes cluster manually.