Add in-line documentation to scripts and methods that
were changed/introduced to support telemetry subscriptions,
which in turn were introduced to support autoflow
tabular views, WTD-614.
Add a subscriber service to handle subscribing to
whole sets of telemetry elements via delegation;
this exposes TelemetrySubscription via a service
which can be retrieved via dependency injection.
Supports the use of this variety of subscription
for autoflow tabular views, WTD-614.
