Add service_conf and llm_factories options to Helm chart (#8607)

### What problem does this PR solve?

### Type of change

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

helm/templates/ragflow.yaml

           - mountPath: /etc/nginx/nginx.conf
             subPath: nginx.conf
             name: nginx-config-volume
+          {{- with .Values.ragflow.service_conf }}
+          - mountPath: /ragflow/conf/local.service_conf.yaml
+            subPath: local.service_conf.yaml
+            name: service-conf-volume
+          {{- end }}
+          {{- with .Values.ragflow.llm_factories }}
+          - mountPath: /ragflow/conf/llm_factories.json
+            subPath: llm_factories.json
+            name: service-conf-volume
+          {{- end }}
         envFrom:
           - secretRef:
               name: {{ include "ragflow.fullname" . }}-env-config
         - name: nginx-config-volume
           configMap:
             name: nginx-config
+        - name: service-conf-volume
+          configMap:
+            name: ragflow-service-config
 ---
 apiVersion: v1
 kind: Service

helm/templates/ragflow_config.yaml

 ---
 apiVersion: v1
 kind: ConfigMap
+metadata:
+  name: ragflow-service-config
+data:
+  {{- with .Values.ragflow.service_conf }}
+  local.service_conf.yaml: |
+    {{- . | toYaml | nindent 4 }}
+  {{- end }}
+  {{- with .Values.ragflow.llm_factories }}
+  llm_factories.json: |
+    {{- . | toPrettyJson | nindent 4 }}
+  {{- end }}
+---
+apiVersion: v1
+kind: ConfigMap
 metadata:
   name: nginx-config
 data:

helm/values.yaml

   EMBEDDING_BATCH_SIZE: 16
 
 ragflow:
+
+  # Optional service configuration overrides
+  # to be written to local.service_conf.yaml
+  # inside the RAGFlow container
+  # https://ragflow.io/docs/dev/configurations#service-configuration
+  service_conf:
+
+  # Optional yaml formatted override for the
+  # llm_factories.json file inside the RAGFlow
+  # container.
+  llm_factories:
+    # factory_llm_infos:
+    # - name: OpenAI-API-Compatible
+    #   logo: ""
+    #   tags: "LLM,TEXT EMBEDDING,SPEECH2TEXT,MODERATION"
+    #   status: "1"
+    #   llm:
+    #     - llm_name: my-custom-llm
+    #       tags: "LLM,CHAT,"
+    #       max_tokens: 100000
+    #       model_type: chat
+    #       is_tools: false
+
+  # Kubernetes configuration
   deployment:
     strategy:
     resources: