[UserAPI] [UserIndicator Plugin] [ExampleUserProvider Plugin] New user api and related functionality (#4538)

* Implements User API and example user plugin

Co-authored-by: John Hill <john.c.hill@nasa.gov>
Co-authored-by: Charles Hacskaylo <charlesh88@gmail.com>
Co-authored-by: Andrew Henry <akhenry@gmail.com>

src/api/api.js

@@ -33,7 +33,8 @@ define([
     './status/StatusAPI',
     './telemetry/TelemetryAPI',
     './time/TimeAPI',
-    './types/TypeRegistry'
+    './types/TypeRegistry',
+    './user/UserAPI'
 ], function (
     ActionsAPI,
     CompositionAPI,
@@ -47,7 +48,8 @@ define([
     StatusAPI,
     TelemetryAPI,
     TimeAPI,
-    TypeRegistry
+    TypeRegistry,
+    UserAPI
 ) {
     return {
         ActionsAPI: ActionsAPI.default,
@@ -62,6 +64,7 @@ define([
         StatusAPI: StatusAPI.default,
         TelemetryAPI: TelemetryAPI,
         TimeAPI: TimeAPI.default,
-        TypeRegistry: TypeRegistry
+        TypeRegistry: TypeRegistry,
+        UserAPI: UserAPI.default
     };
 });