Increased default secondary video size and data rate

In this update, the default XSmall frame size for videos is changed from 90p to 180p, that is, from 160x90 to 320x180 pixels.

The default data rate for XSmall frame size videos is increased from 20 to 25.

With this change, the carousel view, Modern Express Client card view, and undocked video panel view can now produce a larger viewing image, especially with multiple channels.

This change is applicable to both fresh install and upgrade scenarios.