add logging for files

Author: bzantium

MaxText/input_pipeline/_grain_data_processing.py

@@ -36,6 +36,7 @@
 def find_data_files(data_file_pattern):
   data_files = glob.glob(str(Path(data_file_pattern).expanduser().resolve()))
   assert len(data_files) > 0, f"No file found with pattern {data_file_pattern}."
+  max_logging.log(f"Found {len(data_files)} files for train/eval with grain")
   return data_files