Draft: YAML-based configuration in cbm::algo::Unpack.

Depends on !1176 (merged).

First steps for switching to YAML-based parameter initialization in cbm::algo::Unpack.

Currently for STS only. Additional systems will be added when YAML-support becomes available.

Path to parameter file is hard-coded until there is consensus on how to store / pass them. Perhaps another YAML file?

@fweig @v.friese