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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charts/netbird-operator/templates/rbac.yaml

@@ -39,6 +39,7 @@ rules:
   - networkrouters
   - networkresources
   - sidecarprofiles
+  - clusterproxies
   verbs:
   - get
   - patch
@@ -59,6 +60,7 @@ rules:
   - networkrouters/status
   - networkresources/status
   - sidecarprofiles/status
+  - clusterproxies/status
   verbs:
   - get
   - patch