support moving the new side panel

[kinh-nguyen]

From the idea suggested here

Another questionhow can we layout like this?
(side-bar and side-panel are at the same side(left or right), and keep panel in bottom)

Originally posted by @heartacker in microsoft/vscode#141349 (comment)

Could we achieve this with customize-ui? My wish is to have the text I'm editing at the center of the screen, for example currently I have to turn my head left when typing, the side panel is a perfect padding for this.