sorting imports on save; cleanup imports sorting; add isort check (#207)

scripts/run_data_preprocessor.py

@@ -5,6 +5,7 @@ Script to process different dataset types into our format.
 # TODO(ethan): we should write a script here to convert from other datasets to our formats
 # e.g., Blender, LLFF, ShapeNet, DTU
 from typing import List
+
 from hydra import compose, initialize
 
 from nerfactory.data.utils import get_dataset_inputs