WIP: HFOR metadata config
This is an attempt to make the HFOR tool thread-safe by simply moving the initialization to the beginOfEvent method and using the metadata, rather than waiting until the first event and using the event info there.
Important for this migration is that these tools have const methods that we can call during execute. This changes them to be const. Most of the changes are just to do with either removing bookkeeping data (in one case done entirely with ifdefs so that a developer can put it back and check on it later) or passing objects by reference instead of keeping them as member variables, so that the objects are stateless.