add occupancy bookkeeping class and HIPO banks

[baltzell]

To reduce data volume, this adds an occupancy bookkeeping class and engine, with I/O helpers for indexed banks ready for all standard clas12 detectors. The new occupancy banks currently look like this:

        "name": "OCC::FTOF::adc",
        "group": 500,
        "item": 14,
        "info": "Occupancy Bank",
        "entries": [
            { "name":"sector"    , "type":"B", "info":"sector"},
            { "name":"layer"     , "type":"B", "info":"layer"},
            { "name":"component" , "type":"S", "info":"component"},
            { "name":"hits"      , "type":"F", "info":"number of hits"}

• Choose occupancy bank naming.
• Need to use FilteredBank for order-hijacking by denoising
• Check the #-index assumption for all detectors
• Missing detectors
• Note, this ignore negative indices, e.g. BMT/BST
• YAML variable: "prescale"?

The main consumer of these new occupancy banks is clas12-timeline.

Depends on #1380, #1381, #1382, #1383.

[c-dilks]

Is there any way to avoid the DRY violation here, and read occupancy.json somehow?

[baltzell]

That could surely be done.