Feat: Redesign and refactor agent module (#9113)

### What problem does this PR solve?

#9082 #6365

<u> **WARNING: it's not compatible with the older version of `Agent`
module, which means that `Agent` from older versions can not work
anymore.**</u>

### Type of change

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

rag/llm/rerank_model.py

@@ -89,7 +89,7 @@ class DefaultRerank(Base):
 
             torch.cuda.empty_cache()
         except Exception as e:
-            print(f"Error emptying cache: {e}")
+            log_exception(e)
 
     def _process_batch(self, pairs, max_batch_size=None):
         """template method for subclass call"""