Add Acts to AthSimulation
Hi everybody,
if we want to start using the new Muon SensitiveDetectors in AthSimulation, we also need the new ReadoutGeometry which is based on Acts. Probably this MR does not work without atlasexternals!1076 (closed) and an externals bump afterwards, I don't know.
Tagging: @jchapman, @jcatmore, @mbandier, @schaarsc, @akraszna