Add isort to the pre-commit configuration and apply it to the whole project (#595)

* Apply isort to the entire repository
* Fix missing import issues in text_to_entries
* Fix imports in migration files

tests/helpers.py

@@ -1,16 +1,17 @@
-import factory
 import os
 
+import factory
+
 from khoj.database.models import (
-    KhojUser,
-    KhojApiUser,
     ChatModelOptions,
+    Conversation,
+    KhojApiUser,
+    KhojUser,
     OfflineChatProcessorConversationConfig,
     OpenAIProcessorConversationConfig,
     SearchModelConfig,
-    UserConversationConfig,
-    Conversation,
     Subscription,
+    UserConversationConfig,
 )