add rerank model (#969)

### What problem does this PR solve?

feat: add rerank models to the project #724 #162

### Type of change

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

api/db/services/dialog_service.py

@@ -115,11 +115,14 @@ def chat(dialog, messages, stream=True, **kwargs):
     if "knowledge" not in [p["key"] for p in prompt_config["parameters"]]:
         kbinfos = {"total": 0, "chunks": [], "doc_aggs": []}
     else:
+        rerank_mdl = None
+        if dialog.rerank_id:
+            rerank_mdl = LLMBundle(dialog.tenant_id, LLMType.RERANK, dialog.rerank_id)
         kbinfos = retrievaler.retrieval(" ".join(questions), embd_mdl, dialog.tenant_id, dialog.kb_ids, 1, dialog.top_n,
                                         dialog.similarity_threshold,
                                         dialog.vector_similarity_weight,
                                         doc_ids=kwargs["doc_ids"].split(",") if "doc_ids" in kwargs else None,
-                                        top=1024, aggs=False)
+                                        top=1024, aggs=False, rerank_mdl=rerank_mdl)
     knowledges = [ck["content_with_weight"] for ck in kbinfos["chunks"]]
     chat_logger.info(
         "{}->{}".format(" ".join(questions), "\n->".join(knowledges)))
@@ -130,7 +133,7 @@ def chat(dialog, messages, stream=True, **kwargs):
 
     kwargs["knowledge"] = "\n".join(knowledges)
     gen_conf = dialog.llm_setting
-    
+
     msg = [{"role": "system", "content": prompt_config["system"].format(**kwargs)}]
     msg.extend([{"role": m["role"], "content": m["content"]}
            for m in messages if m["role"] != "system"])