Pull @ohif/ui ViewportPane into separate component and expose

platform/ui/src/components/index.js

@@ -43,6 +43,7 @@ import Typography from './Typography';
 import Viewport from './Viewport';
 import ViewportActionBar from './ViewportActionBar';
 import ViewportGrid from './ViewportGrid';
+import ViewportPane from './ViewportPane';
 
 export {
   Button,
@@ -91,4 +92,5 @@ export {
   Viewport,
   ViewportActionBar,
   ViewportGrid,
+  ViewportPane,
 };