Pushing some first concept for a possible DAOD level slim.
This is using the re-packing of all trigger features into a Particle container we can put in the DAOD, rather than keeping around all the
HLT_XXX physics collections.
It works around the fact that derivation level thin/slim/skim does not work well with the navigation at the moment (no good remapping procedure)
Run time tests indicate a 50% saving (down to 6 kb/event) with the current set of chains in Run 3 which we use for trigger matching. This is 718 chains.
Note that for now we store both formats. We need to confirm that they are equivalent to each other before deciding which to keep! We need to decide before the main MC production happens in May.