Optimisation in passing callback manager (#94)

* Change token counter implementation & support embedding token counting (defaults to tiktoken)

* Refactor code

* Add a todo

* Pass callback manager directly

Author: gaya3-zipstack

src/unstract/sdk/vector_db.py

@@ -136,7 +136,7 @@ def get_vector_store_index_from_storage_context(
             show_progress=show_progress,
             embed_model=self._embedding_instance,
             node_parser=parser,
-            callback_manager=callback_manager,
+            callback_manager=self._embedding_instance.callback_manager,
         )
 
     def get_vector_store_index(self, **kwargs: Any) -> VectorStoreIndex:
@@ -145,7 +145,7 @@ def get_vector_store_index(self, **kwargs: Any) -> VectorStoreIndex:
         return VectorStoreIndex.from_vector_store(
             vector_store=self._vector_db_instance,
             embed_model=self._embedding_instance,
-            callback_manager=kwargs.get("callback_manager"),
+            callback_manager=self._embedding_instance.callback_manager,
         )
 
     def get_storage_context(self) -> StorageContext: