qa-physics: bin QA by scaler readouts, not 5-files

[c-dilks]

Perform the physics QA in sets ("bins") of consecutive events between a number of scaler readouts. This number may be run-period dependent, and could be chosen such that the QA bin size is similar to our current DST 5-file size.

This would resolve JeffersonLab/clas12-qadb#9 and return a more accurate calculation of accumulated FC charge per QA bin.

This would not be a breaking change to users, since they query the QADB by event number.

We could also do away with the deprecated binning by event numbers idea (see skim option of monitorRead.groovy)