feat: Add CS3D WSI and Video Viewports and add annotation navigation for MPR (#4182)

platform/app/.webpack/webpack.pwa.js

@@ -35,6 +35,8 @@ const setHeaders = (res, path) => {
   }
   if (path.indexOf('.pdf') !== -1) {
     res.setHeader('Content-Type', 'application/pdf');
+  } else if (path.indexOf('mp4') !== -1) {
+    res.setHeader('Content-Type', 'video/mp4');
   } else if (path.indexOf('frames') !== -1) {
     res.setHeader('Content-Type', 'multipart/related');
   } else {