Draft: TRD cluster finder restructuring

@a.bercuci for reference.

To be clear: This is precursor work for a online-capable port. Hence, lots of the functionality of the original classes has been stripped away, in particular all of the event-by-event stuff. This is a working branch and is not intended to be merged. The online-capable classes will in the end be distinct from the original ones and not replace them during merge.

You will notice that I have moved the "format digi" step into a dedicated function, which I falsely call CalibDigi. This is now part of CbmTrdClusterFinder instead of CbmTrdModuleRec2D. The actual cluster building then works on tuples [chT, chR, tm, row, id] as discussed in !1605 (closed).

The version of the code here already sees some drastic performance gains, to a point where processing full timeslices is possible in some cases.