chore: custom data refine (#864)

* chore: print up to 100 columns in simple mode

* fix: check content for model dump

* chore: add show_nan_columns config

rdagent/app/data_science/conf.py

@@ -44,6 +44,7 @@ class DataScienceBasePropSetting(KaggleBasePropSetting):
     rule_base_eval: bool = False
     sample_data: bool = True
     use_raw_description: bool = False
+    show_nan_columns: bool = False
 
     #### model dump
     enable_model_dump: bool = False