Secondary Windows have separate Zoom Level

[tsmaeder]

Bug Description:

When I open a secondary windows (for example, a terminal), the windows opens at the default zoom level. My expectation would be that the window opens at the same zoom level as the main window it has been created from.
There are a couple of related issues here: for example, we don't have a menu bar nor a command palette in the secondary window. So how would we adjust the zoom level of the secondary window?

Steps to Reproduce:

1. Zoom the main browser window to 200%
2. Open a terminal
3. Move the terminal to a secondary window by clicking the icon in the view toolbar
4. Observe: the window opens at 100% zoom.

Additional Information

• Operating System: Windows
• Theia Version: 1.31.0