feat: tab / stack all windows on workspace (monocle view)

[arkonbob]

Monocle / single window layout Some tiling window managers (generally those based on pre-canned layouts such as Xmonad on Linux and Amethyst on Mac) support a single window or 'monocle' layout. In this layout, whichever window has focus fills the whole tiling area. Essentially the same thing can be achieved in Forge, by placing all windows in a tabbed layout and hiding the tabs. The 'Toggle tabbed layout' shortcut can then be used to switch between tiled or fullscreen windows. However, 'Toggle tabbed layout' has no effect if the windows have not first been manually placed in a tabbed layout (by dragging them one atop the other).

Desired Solution All the tileable windows on a workspace are placed in tabbed layout when 'Toggle tabbed layout' is invoked, regardless of whether any tabbed layout has been configured prior.