Allow multiple track writers, dump fullscan tracks for trigger studies

We want to try out b-tagging on fullscan "fast" trigger tracking. This merge request does a few things:

• Add track association between trigger jets and fullscan fast tracking
• Make the track dumping more configurable, and allow multiple track writers

The second change meant a bit of restructuring for the configuration files: the track configuration is now a list, with each entry specifying how many tracks to save, the sort order, the source for the tracks, the selection, etc. An empty list here means no tracks will be saved.

I updated all the configurations together. The jq command to update them was

jq  --indent 4 '.tracks = [ {"n_to_save": .n_tracks_to_save, "selection": .track_selection, "sort_order":.track_sort_order, "source":"btagging", "input_name": "BTagTrackToJetAssociator", "output_name": "tracks", "variables": .variables.track} ] | del(.n_tracks_to_save) | del(.track_selection) | del(.track_sort_order) | del(.variables.track)'