text: Title: Is it possible to make is_deleted field redefined and optional?
  Body: https://github.com/igorbenav/fastcrud/blob/adf9ab08c6d7b39b303374a430623846bc6548d3/fastcrud/crud/fast_crud.py#L1697
  
  It would be convenient to make this field redefined to self.is_deleted_column and optional, because in some cases, one deleted_at_column field is enough to understand that the record has been deleted.