Refactor vtk extension; re-add to app

extensions/ohif-vtk-extension/src/index.js

@@ -1,7 +1,24 @@
+import OHIFVTKViewport from './OHIFVTKViewport.js';
+import commandsModule from './commandsModule.js';
+// This feels weird
 import loadLocales from './loadLocales';
+import toolbarModule from './toolbarModule.js';
 
-import OHIFVTKExtension from './OHIFVTKExtension.js';
+export default {
+  /**
+   * Only required property. Should be a unique value across all extensions.
+   */
+  id: 'vtk',
+
+  getViewportModule() {
+    return OHIFVTKViewport;
+  },
+  getToolbarModule() {
+    return toolbarModule;
+  },
+  getCommandsModule() {
+    return commandsModule;
+  }
+};
 
 loadLocales();
-
-export default OHIFVTKExtension;