Add spruce lines for B2HPi0 with Dalitz pi0 decays

This MR add two new lines for B^+ \to K^+ \pi^0 and B^+ \to \pi^+ \pi^0 decays with \pi^0 \to e^+ e^- \gamma, based on the experience of reconstructing D^+ \to \pi^+ \pi^0 decays in the Charm group. We've seen that the yield per inv fb increased by a factor of 10 between Run2 and Run3 for \pi^0 \to e^+ e^- \gamma decays, therefore it might now be worth including this final state for the B^+ \to h^+ \pi^0 decays. The yield will be small due to the low efficiency, but the sample would be softer than the calorimeter \pi^0 approach.

The lines has been run over all events in the sprucing testing snippet and the bandwidth is as follows:

Line	Eff	Rate
BuToKpPi0_Dalitz	2/371018 = 0.0000054	0.41 Hz
BuToPipPi0_Dalitz	3/371018 = 0.0000081	0.61 Hz

file_size = 171k

b/w (GB/s) = input rate (75.49 kHz for this HLT2 output file) x 0.171 (MB) / 371018

b/w (GB/s) = 0.000035 GB/s = 35 (KB/s)

Hlt/Hlt2Conf/python/Hlt2Conf/lines/bnoc/bTohh.py

@@ -14,7 +14,7 @@
 
 from GaudiKernel.SystemOfUnits import (
     MeV,  # will be needed once the full set of lines is back
-    picoseconds,
+    picosecond,
 )
 
 from Hlt2Conf.lines.bnoc.builders import b_builder, basic_builder