wezterm: Add key to detach selected pane into new window

`<leader><c-s-Q>` activates the pane selector and lets you decide which
pane to detach from the current _window_ and move to a new one.

This mirrors the `<leader><c-q>` mapping moving a pane to a new tab,
only 'bigger', thus using shift in addition.

The binding is a little awkward, but with how rarely I have needed to
use it this was fine for me so far.

terminal/.config/wezterm/maps.lua

@@ -52,6 +52,11 @@ local keys = {
 		mods = "LEADER|CTRL",
 		action = act.PaneSelect({ mode = "MoveToNewTab" }),
 	},
+	{
+		key = "Q",
+		mods = "LEADER|CTRL",
+		action = act.PaneSelect({ mode = "MoveToNewWindow" }),
+	},
 	{
 		key = "R",
 		mods = "LEADER",