[API] Support dynamic telemetry metadata (#1941)

* [API] Support dynamic telemetry metadata

Add support for dynamic telemetry metadata via custom telemetry
metadata providers.  

The metadata provider API should be considered unstable in it's
current invocation.

* Perform deprecation checking at runtime
* SWG uses telemetry metadata provider
* Don't throw with no matched metadata provider
* Update API docs
* Add license header
* Combine metadata providers with general telemetry providers
* Replace `TelemetryAPI.canProvideTelemetry` with
`TelemetryAPI.isTelemetryObject`.  
* CanProvideTelemetry is deprecated
* Change SWG inputs to numberfield

platform/features/table/src/controllers/TelemetryTableController.js

@@ -399,14 +399,14 @@ define(
             var compositionApi = this.openmct.composition;
 
             function filterForTelemetry(objects) {
-                return objects.filter(telemetryApi.canProvideTelemetry.bind(telemetryApi));
+                return objects.filter(telemetryApi.isTelemetryObject.bind(telemetryApi));
             }
 
             /*
              * If parent object is a telemetry object, subscribe to it. Do not
              * test composees.
              */
-            if (telemetryApi.canProvideTelemetry(this.domainObject)) {
+            if (telemetryApi.isTelemetryObject(this.domainObject)) {
                 return Promise.resolve([this.domainObject]);
             } else {
                 /*