### What problem does this PR solve?
Adds OpenSearch support to the RAGFlow Helm chart based on
https://github.com/infiniflow/ragflow/pull/7140 and the existing
Elasticsearch support in the Helm chart.
### Type of change
- [X] New Feature (non-breaking change which adds functionality)
### 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)
