Add support for 16 OH in the CTP7 GE2/1 flavor

This MR is a follow-up on !171 (closed) after offline discussions. While supporting 18 OH on the CTP7 GE2/1 flavor - and up to 24 OH in 0xBEFE - is technically possible and allows to entirely "fill" the 3 CTP7 CXP, there is little/no practical use case for this.

Compared to !171 (closed), only the first commit is kept and enhanced to also unify the DAQ module signals and register to 16 OH. While not tested on hardware, no issues are expected provided the builds pass considering that the larger update to 18 OH worked like a charm on the production system at P5 during the GE2/1 trolley test and initial commissioning.