add toggle focus between floating and tiled layers

Adds focus_floats(), toggle_focus_float_tiled(), and their IPC
bindings so users can bind a key to swap focus between the floating
and tiled layers.

toml-config/src/config/parsers/action.rs

@@ -158,6 +158,7 @@ impl ActionParser<'_> {
             "focus-below" => FocusLayerRel(LayerDirection::Below),
             "focus-above" => FocusLayerRel(LayerDirection::Above),
             "focus-tiles" => FocusTiles,
+            "toggle-float-focus" => ToggleFocusFloatTiled,
             "create-mark" => CreateMark,
             "jump-to-mark" => JumpToMark,
             "clear-modes" => PopMode(false),