Adding support for non-top level and special named jet- and track collections
Summary
This MR introduces the following changes
- Add support for non-top level jet and track collections. This can be set over the "collecton_name" option in the "preparation" part of the preprocessing config now. After the preparation step, the jet- and track collections will always be top level.
- Add support for different named jet collections. The default is "jets" which can be set over the "jets_name" option in the "preparation" part of the preprocessing config now. After the preparation step, the jet collection is always top level and is called "jets".
- Documentation for the new options is also added.