Add new resource for Kubernetes API proxy (#279)

This adds a new resource which deploys a Kubernetes API server proxy
that can be used to access the API server without tokens through
Netbird.

Part of #274 

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## Summary by CodeRabbit

* **New Features**
* Added ClusterProxy custom resource for cluster API proxying
capabilities

* **Documentation**
  * Added ClusterProxy API reference documentation with schema details

* **Examples**
* Added example ClusterProxy configuration and RBAC setup for cluster
proxy targets

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PROJECT

@@ -115,4 +115,12 @@ resources:
   kind: SidecarProfile
   path: github.com/netbirdio/kubernetes-operator/api/v1alpha1
   version: v1alpha1
+- api:
+    crdVersion: v1
+    namespaced: true
+  controller: true
+  domain: netbird.io
+  kind: ClusterProxy
+  path: github.com/netbirdio/kubernetes-operator/api/v1alpha1
+  version: v1alpha1
 version: "3"