Split topic values into individual telemetry points

[AWatk]

combine with #27 for properly referencing a topic value and then change object provider to return an individual telemetry object for each value. Topics will then be folders containing these telemetry points.

[AWatk]

Splitting each topic field into its own telemetry point means that topics that contain other topics as a field will have nested folders.

This is necessary for visualization (I think) because there is a difference between a telemetry datum object (which needs to contain only a single value) and an openMCT form that can contain any number of telemetry datums that can be displayed on the same graph.

see the sine generator example for the use of such a form.
the generator can be installed via `openmct.install(openmct.plugins.Generator())
plugin code is here https://github.com/nasa/openmct/tree/a51b9bc63f738e04cb877626371b07bd6b924a27/example/generator

[AWatk]

This complicates #24

Perhaps the form to visualize a topic should be auto-generated as well? Then the publishing interface can just be on that form instead of tied to a telemetry point.