[Improvement] Use SQLite for chat memory (#910)

Co-authored-by: Deven Patel <deven298@yahoo.com>

embedchain/memory/utils.py

@@ -0,0 +1,35 @@
+from typing import Any, Dict, Optional
+
+
+def merge_metadata_dict(left: Optional[Dict[str, Any]], right: Optional[Dict[str, Any]]) -> Optional[Dict[str, Any]]:
+    """
+    Merge the metadatas of two BaseMessage types.
+
+    Args:
+        left (Dict[str, Any]): metadata of human message
+        right (Dict[str, Any]): metadata of ai message
+
+    Returns:
+        Dict[str, Any]: combined metadata dict with dedup
+        to be saved in db.
+    """
+    if not left and not right:
+        return None
+    elif not left:
+        return right
+    elif not right:
+        return left
+
+    merged = left.copy()
+    for k, v in right.items():
+        if k not in merged:
+            merged[k] = v
+        elif type(merged[k]) != type(v):
+            raise ValueError(f'additional_kwargs["{k}"] already exists in this message,' " but with a different type.")
+        elif isinstance(merged[k], str):
+            merged[k] += v
+        elif isinstance(merged[k], dict):
+            merged[k] = merge_metadata_dict(merged[k], v)
+        else:
+            raise ValueError(f"Additional kwargs key {k} already exists in this message.")
+    return merged