Generate python optsfile boilerplate

Working example (BtoChicKst.py):

from Configurables import DaVinci
from AnalysisHelpers.decaytreetuple import configure_dtt
import os, yaml
from pathlib import Path
config_file = Path(os.environ["ANALYSIS_PRODUCTIONS_BASE"]) / "wizardtesting"/ "BtoChicKst.yaml"
config = yaml.safe_load(open(config_file, "rb"))
dtt = configure_dtt(config)
DaVinci().UserAlgorithms += [dtt]