Added Bash script for test

LHCbG4Tests/G4GammaToDiLeptonConversionTest/scripts/run_gammaconv_test.sh

+#!/usr/bin/env sh
+
+echo "Running G4GammaConversionTest..."
+python $G4GAMMATODILEPTONCONVERSIONTESTROOT/scripts/G4GammaToDiLeptonConversionTest.py --energies "[10, 100, 1000]" --thickness "[0.3, 1, 10]"
+echo "Test Complete."