Add support for LangServe

[eolivelli]

As running LangChain apps in LangStream is really easy, we should now support deploying LangServe
https://github.com/langchain-ai/langserve

Running LangServe within a LangStream clusters makes running LangChain and LangServe on Kubernetes in production super easy.

Also LangSteeam will add the security layer of the gateway and add all the scalability of kubernetes