Add etac->hadron builders in bandq directory, and use thor functions to redefine bandq builders

This MR works together with Phys!976 (merged) and Rec!2505 (merged). These three MRs need to be tested and merged together.

Currently most of the bandq trigger/sprucing are related to dimuon pairs. Start to populate the lines with other combiners. Etac -> hadrons as a starting point.

At the same time, we would like to start to use Thor functions to redefine existing bandq builders. Several issues need to be solved:

1. (To solve in Rec!2486 (closed).) F.BPVLTIME seems to return a too small value. A known issue mentioned in Rec#204.
2. (Solved when testing and merging Rec!2505 (merged) together with this MR) BPVDLS not in Thor. A temporary solution is to use the FDCHI2 variable F.BPVFDCHI2(pvs), and assume significance = sqrt(chi2).
3. (solved now by cutting the input tracks for dimuon combiner.) In dimuon builders, we start from the basic dimuon combiner make_dimuon_base in standard_particles, then use CHILDCUT, MINTREE and MAXTREE to cut the muons. Seems these functions are not supported in Thor. A potential solution is to define a new combiner, and use F.SUM, F.MIN, F.MAX or directly cut input muons; but maybe there are more beautiful solutions. (Try new combiners first.)

A few buggy functions of existing thor functions are commented out:

F.X does not work no matter we put it in a combination code, a vertex code or just as a single particle filter.

F.MINIP triggers a segmentation break for a few events.

Etac related things are also WIP. Plan is to have etac -> ppbar, etac -> 4 hadrons as builders, write Lb2etacpK as our first etac related sprucing line, and test the sprucing performance using output of Topo2,3,4 body HLT2 lines. Need to apply for corresponding MC samples.

FYI @ngrieser @gcavalle @lan .

BandQ WG Sprucing lines - related to DPA task https://gitlab.cern.ch/lhcb-dpa/project/-/issues/78.