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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config/crd/kustomizeconfig.yaml

@@ -0,0 +1,12 @@
+# This file is for teaching kustomize how to substitute name and namespace reference in CRD
+nameReference:
+- kind: Service
+  version: v1
+  fieldSpecs:
+  - kind: CustomResourceDefinition
+    version: v1
+    group: apiextensions.k8s.io
+    path: spec/conversion/webhook/clientConfig/service/name
+
+varReference:
+- path: metadata/annotations