@W-22468107 - support local module imports in datacustomcode run

[diksha-sf]

Importing local Python modules failed from the same directory. For example, for the below directory structure, if from utility.py we import helper_function() in entrypoint.py, it failed with ImportError: No module named 'utility'.
my_function/
|── entrypoint.py
|── utility.py

The add_py_folder() function in src/datacustomcode/run.py only added the py-files/ subdirectory to sys.path, but not the entrypoint's own directory.

Solution: Added both py-files/ (if exists) and entrypoint directory

if py_folder.exists():
   sys.path.insert(0, str(py_folder))
sys.path.insert(0, str(entrypoint_dir))