Move AdcChannelMetric channel status retrieval out of ctor

[dladams]

ADcChannelStatus has a method initialize that fetches the status for each channel. It is being called from the ctor but needs to be called later and each event if we are going to move to context-dependent status values. See duneprototypoes issue 20.

[dladams]

Fcl option PlotUsesStatus is int but was used as bool to indicate whether or not plots should include channels status info. This has been enhanced so nonzero value indicate the caching:

• 1 - No caching. Channel status service is called for each channel each time tool is called (i.e. each event).
• 2 - Channel status is cached in the ctor (old behavior). Presumably existing tools will default to no caching.

I tested and verified this work. See https://github.com/DUNE/duneprototypes/issues/20.