fix: 🐛 Fail gracefully on an MPR load error (#1992)

* feat: 🎸 Update react-vtkjs-viewport usage to use requestPool

* Fix import of react-vtkjs-viewport to cornerstone-tools path.

* Increase maximum load time of MPR test now we are throttling requests.

* fix: 🐛 Fail gracefully on an MPR load error

* Respond to reviewer comments.

extensions/vtk/src/LoadingIndicator.js

@@ -32,16 +32,16 @@ class LoadingIndicator extends PureComponent {
             </div>
           </div>
         ) : (
-            <div className="imageViewerLoadingIndicator loadingIndicator">
-              <div className="indicatorContents">
-                <p>
-                  {this.props.t('Loading...')}
-                  <i className="fa fa-spin fa-circle-o-notch fa-fw" />
-                  {percComplete}
-                </p>
-              </div>
+          <div className="imageViewerLoadingIndicator loadingIndicator">
+            <div className="indicatorContents">
+              <p>
+                {this.props.t('Loading...')}
+                <i className="fa fa-spin fa-circle-o-notch fa-fw" />
+                {percComplete}
+              </p>
             </div>
-          )}
+          </div>
+        )}
       </React.Fragment>
     );
   }