cmd/k8s-operator: allow to install operator via helm (#9920)

Initial helm manifests.

Updates tailscale/tailscale#9222

Signed-off-by: Irbe Krumina <irbe@tailscale.com>
Co-authored-by: Maisem Ali <maisem@tailscale.com>

cmd/k8s-operator/deploy/chart/templates/oauth-secret.yaml

@@ -0,0 +1,13 @@
+# Copyright (c) Tailscale Inc & AUTHORS
+# SPDX-License-Identifier: BSD-3-Clause
+
+{{ if and .Values.oauth .Values.oauth.clientId -}}
+apiVersion: v1
+kind: Secret
+metadata:
+  name: operator-oauth
+  namespace: {{ .Release.Namespace }}
+stringData:
+  client_id: {{ .Values.oauth.clientId }}
+  client_secret: {{ .Values.oauth.clientSecret }}
+{{- end -}}