B2taunu with btracking lines

HLT2 lines for B2tau(23pinu)nu with B-tracking. Added to semileptonic lines, with persistreco=True (going into FULL stream).

Needs Rec!2868 (merged), LHCb!4208 (merged), Detector!462 (merged), lhcb-datapkg/PRConfig!339 (merged)

needs gaudi/Gaudi!1489 (merged) and lhcb-datapkg/PRConfig!339 (merged) to be merged (and for v37?)

FYI: @sklaver, @mmulder

Standard rate test (upgrade_minbias_hlt1_filtered; inclusive is all semileptonic lines):

Line:    Hlt2SLB_BToDPiPi_DToKPiPi_BTrackingDecision                     Incl: 0.0 +/- 0.0 kHz, Excl: 0.0 +/- 0.0 kHz
Line:    Hlt2SLB_BToTauNu_TauToPiPiPiNu_BTrackingDecision                Incl: 0.77087 +/- 0.2912 kHz,  Excl: 0.44049 +/- 0.2202 kHz

NOTE: for Sprucing still to be decided, add in later MR? Following !2360 (merged) at least. Persistreco has similar consideration, in principle there for isolation. The HF track objects do need to be persisted (again). VP raw banks preferably too.

See for more info also slides