Unclear TrmWithEmptyFragment warning message

[alessandrothea]

Warning messages generated when readout request windows have no match in the latency buffer are comprehensive but confusing at the same time. They typically look like

SourceID[subsystem: Detector_Readout id: 203] Trigger Matching result with empty fragment: TS match result on link 203: Trigger number=1 Oldest stored TS=106355421074640907 Start of window TS=106355421074639307 End of window TS=106355421074639371 Estimated newest stored TS=106355421269397515 Requestor=fragment_queue

While absolute values are useful, they're difficult to interpret in concrete terms (i.e. how "off" the readout request was wrt the LB boundaries).
Useful infos would be (using obvious abbreviations):

• SoW to OS distance
• EoW to OS distance
• ENS to OS distance

It would be nice to publish these quantities to Opmon for every readout request, in fact.