Don't try to format non-numeric values; rather, just echo them back
directly. This is to allow simple printing of strings when received
on a telemetry subscription. Performed in the context of WTD-644
(since the WARP Server returns many such strings.)
Move implementation of formatter used for display
of domain values out of plot, and into the telemetry
bundle, from which it can be exposed as a general-use
service. WTD-599.
