Add Helm chart deployment method (#3815)

### What problem does this PR solve?

Add's a Helm chart for deploying RAGFlow on Kubernetes. 

Closes #864. 

### Type of change

- [X] New Feature (non-breaking change which adds functionality)

helm/templates/tests/test-connection.yaml

@@ -0,0 +1,17 @@
+apiVersion: v1
+kind: Pod
+metadata:
+  name: "{{ include "ragflow.fullname" . }}-test-connection"
+  labels:
+    {{- include "ragflow.labels" . | nindent 4 }}
+  annotations:
+    "helm.sh/hook": test
+spec:
+  containers:
+    - name: wget
+      image: busybox
+      command:
+      - 'wget'
+      args:
+      - {{ printf "%s.%s.svc" (include "ragflow.fullname" .) .Release.Namespace }}
+  restartPolicy: Never