[Frontend] Add splash screen manager

Add a runtime extension that detects the splash screen and triggers a fade out
after the application has loaded.  Once the fade out has ended, it removes the
element from the page.

Related to https://github.com/nasa/openmctweb/issues/164

platform/commonUI/general/bundle.js

@@ -24,6 +24,7 @@
 define([
     "./src/services/UrlService",
     "./src/services/PopupService",
+    "./src/SplashScreenManager",
     "./src/StyleSheetLoader",
     "./src/UnsupportedBrowserWarning",
     "./src/controllers/TimeRangeController",
@@ -52,6 +53,7 @@ define([
 ], function (
     UrlService,
     PopupService,
+    SplashScreenManager,
     StyleSheetLoader,
     UnsupportedBrowserWarning,
     TimeRangeController,
@@ -117,6 +119,12 @@ define([
                         "notificationService",
                         "agentService"
                     ]
+                },
+                {
+                    "implementation": SplashScreenManager,
+                    "depends": [
+                        "$document"
+                    ]
                 }
             ],
             "filters": [