[Search] Use new composition in search

Use private parts of new composition API for generic search indexer
so that all objects are properly accessible in search results.

Also prevent ROOT object from getting indexed but still traverse
composition.  That way, "The root object" no longer shows in search
results.

Update tests to cover changes.

Fixes #1579

platform/search/bundle.js

@@ -100,7 +100,8 @@ define([
                         "modelService",
                         "workerService",
                         "topic",
-                        "GENERIC_SEARCH_ROOTS"
+                        "GENERIC_SEARCH_ROOTS",
+                        "openmct"
                     ]
                 },
                 {