Draft: TRD cluster / hit finder discussions.

Draft MR to discuss details concerning CbmTrdClusterFinder and CbmTrdHitProducer with @a.bercuci who appears to be the current maintainer ( @praisig seems to be the original author but is no longer with us).

The goal is to better understand the current TRD hitfinder, to aid in the development of an online-capable version.

@d.smith yes I will assume the overlooking of the TRD software until we will discuss it in the TRD group. Agree @p.kaehler ?