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/mysql-config.yaml

@@ -0,0 +1,9 @@
+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: mysql-init-script
+data:
+  init.sql: |-
+    CREATE DATABASE IF NOT EXISTS rag_flow;
+    USE rag_flow;