Add HLT2 line Bu2DspPPbar

Add one HLT2 line of

B^{+}\to D_{s}^{+}p\bar{p}

for spectroscopy study.

The rate is estimated by hlt1_filtered 2024 minbias samples as

rate_MinBias_BuToDspPPbar
#= 1110033.0 Sum= 83.0 Eff = ( 0.007 +/- 0.001 )% | rate = ( 89.7 +/- 9.8 ) Hz

The related builders are quoted from b_for_spectroscopy and c_to_hadrons.

Given the fact there is no need for persistreco, this line isn't included in the make_Bu containter, but taken as an independent line and registered in hlt2_bandq directly.

And its mass for b-meson extends to cover the Bc mass since the rate is still within the limit.

FYI @jfu