[GPU integration] enable new AdePT and G4HepEm physics list

This MR adds the G4HepEm and AdePT physics lists Opt2_HepEm and Opt2_AdePT.

Depends on the following PRs in Gauss:

• !1185
• !1184
• !1126

In Gaussino:

• Gaussino/Gaussino!208 (merged)
• Gaussino/Gaussino!197
• Gaussino/Gaussino!192
• Gaussino/Gaussino!176
• Gaussino/Gaussino!175

In LHCb/Geant4:

• Geant4!119
• Geant4!117

G4HepEm:

• https://github.com/mnovak42/g4hepem/pull/127 (not needed anymore, latest master is perfectly fine)

AdePT

• this branch: https://github.com/SeverinDiederichs/AdePT/tree/lhcb_hardcoded_steppingaction