Improve SGInputLoaderCfg and set it up for InDetOverlay

Improve SGInputLoaderCfg to be able to parse standard formats of input/outputs strings, either separated by # or /. Add Input.FailOnUnknownCollections to prevent loading missing input and Scheduler.AutoLoadUnmetDependencies to not schedule loading items automatically.

Also set it up for InDetOverlay.

/cc @jchapman @rbielski