allow moving duet to the sides of the screen and make it resizable

[gtaltatra]

Duet on the bottom seems to be very questionable in terms of actual usage. Many sites often use bottom navigation elements, there is also a tab group bar that also has its height but only if there are at least two tabs in a group So a better option in my opinion would be to move it on the right or the left side of the screen where navigation elements are rare depending on if a user uses swipe gestures and which side he decides to swap for the duet instead. However, even on the sides there are sometimes navigation elements such as menu buttons that are usually placed on the higher ends of the sides, so it would be nice if the duet could be also made a little shorter at one end.