Add Trd2d for event building

The MR is aimed at fixing a problem appeared for the Trd2d with the advent of mCBM 2021 data taking but affecting the whole TRD group on the longer run; namely the accommodation of 2 pad-plane pick-up electrode topologies (rectangular and triangular) operated by 2 types of FEEs (SPADIC and FASP). Since this is a particularity of only the TRD system the modifications are somehow wider affecting tangentially also parts of the general steering code.

Basically the MR aims at the following :

• Extend functionality of BuildRawEvents (Algo/Task) to incorporate also data from Trd2d
• Add data descriptors for Trd2d in the CbmDefs
• add a proposal for a steering script for event building for mcbm 2021