Provide a javascript version for https://python.langchain.com/docs/modules/data_connection/retrievers/ensemble/

[madmed88]

Checked

• I searched existing ideas and did not find a similar one
• I added a very descriptive title
• I've clearly described the feature request and motivation for it

Feature request

Currently Ensemble Retriever is only available in Python. This is a useful retriever that is not available in Javascript.
https://python.langchain.com/docs/modules/data_connection/retrievers/ensemble/

Motivation

feature parity between Python and Javascript

Proposal (If applicable)

No response