feat: RAG API Server to use Async/Await

[ishaansehgal99]

Reason for Change:
Endpoints are currently sequentially blocking synchronous. After review we use async-await pattern correctly.

[zhuangqh]

=========================== short test summary info ============================
FAILED presets/ragengine/tests/vector_store/test_chromadb_store.py::TestChromaDBVectorStore::test_query_documents - TypeError: 'coroutine' object is not subscriptable
FAILED presets/ragengine/tests/vector_store/test_faiss_store.py::TestFaissVectorStore::test_query_documents - TypeError: 'coroutine' object is not subscriptable
================== 2 failed, 15 passed, 35 warnings in 29.66s ==================
make: *** [Makefile:109: rag-service-test] Error 1

please take a look

[Fei-Guo]

async def health_check():

As we discussed, should we remove async here?

[Fei-Guo]

This is in-memory operation, right? Do we need await?

[zhuangqh]

i think this one is not awaitable.

[ishaansehgal99]

this is llamaindex insert - llama_index/core/indices/base.py
yes it is not awaitable

    def insert(self, document: Document, **insert_kwargs: Any) -> None:
        """Insert a document."""
        with self._callback_manager.as_trace("insert"):
            nodes = run_transformations(
                [document],
                self._transformations,
                show_progress=self._show_progress,
                **insert_kwargs,
            )

            self.insert_nodes(nodes, **insert_kwargs)
            self.docstore.set_document_hash(document.get_doc_id(), document.hash)