feat(VideoContainer) add option to avoid cropping focused video

interface_config.js

     // Determines how the video would fit the screen. 'both' would fit the whole
     // screen, 'height' would fit the original video height to the height of the
     // screen, 'width' would fit the original video width to the width of the
-    // screen respecting ratio.
+    // screen respecting ratio, 'nocrop' would make the video as large as
+    // possible and preserve aspect ratio without cropping.
     VIDEO_LAYOUT_FIT: 'both',
 
     /**

modules/UI/videolayout/VideoContainer.js

     }
 
     const aspectRatio = videoWidth / videoHeight;
+    const videoSpaceRatio = videoSpaceWidth / videoSpaceHeight;
 
     switch (videoLayoutFit) {
     case 'height':
         return [ videoSpaceHeight * aspectRatio, videoSpaceHeight ];
     case 'width':
         return [ videoSpaceWidth, videoSpaceWidth / aspectRatio ];
+    case 'nocrop':
+        return computeCameraVideoSize(
+            videoWidth,
+            videoHeight,
+            videoSpaceWidth,
+            videoSpaceHeight,
+            videoSpaceRatio < aspectRatio ? 'width' : 'height');
     case 'both': {
-        const videoSpaceRatio = videoSpaceWidth / videoSpaceHeight;
         const maxZoomCoefficient = interfaceConfig.MAXIMUM_ZOOMING_COEFFICIENT
             || Infinity;