Mod reco

Changed reconstruction stage to a similar scheme as the new oscillation stage (base service with several derived services). This should allow for easier adding of alternative reco methods. E.g. parametrized reco, which is to follow soon.
It seems this service does not (yet?) support `e_reco_scale` and `cz_reco_scale`. In this case, it should throw a `ValueError` if either of the two is not equal to 1. If the plan is to never have this service support them, just omit them from `_get_reco_kernels`.