Fixes to enable testing by third party applications (#2523)

* Initial commit of telemetry table spec

* Fix errors found by running Open MCT app headless

* Do not double install import-export plugin

* Changes to allow Open MCT to be initialized more than once without binding to window.document

* Remove table spec accidentally added

platform/import-export/bundle.js

@@ -72,7 +72,6 @@ define([
                     ]
                 }
             });
-            openmct.legacyRegistry.enable('platform/import-export');
         };
     };
 });