GenerateMenuMT Cleanup, 22.0 branch (2022.07.08.)
Made the TriggerMenuMT.HLT.Config.GenerateMenuMT module "importable" in other projects than full Athena.
This is necessary for the AthDerivation project in master. But as people complained in !54460 (closed) about changing trigger code in master directly, let's collect this into 22.0 first...