Add "window to master" shortcut for half layout

[74naUM2EMP]

Is your feature request related to a problem? Please describe.
In Bismuth there was a "window to master" shortcut for the master-stack layout, which would move the active window to the master position. In the half layout with insertion point "right", this would be the single window on the left.

Describe the solution you'd like
A shortcut which switches the position of the active window with the window on the "non insertion point" side - the "master" position. If there are multiple windows in the "master" move them all to the stack and replace with the active window.

Describe alternatives you've considered
Move the active window with "Insert left", switch focus to the other window in the "master" and use "Insert right". However, this is 3 operations, which is cumbersome.

[zeroxoneafour]

I may rework the half layout to be a more restrictive master/stack layout, or add a master/stack layout in addition to the half layout. A keybind for this will not come directly to the half layout as it would impede the flexibility of the layout, but I'll keep this in mind for v1.1.