wayland: implement scaling

This involves many subsystems:

- config:
    - allow setting the connector scale
    - allow setting the cursor size
- cursors:
    - load server cursors for all requested sizes and scales
- wl_surface:
    - track the output the surface belongs to
    - send wl_surface.enter/leave
- wl_output:
    - implement wl_output.scale
- text:
    - pre-render texts for all used scales
- renderer:
    - properly align scale textures and rectangles
- wp_fractional_scale:
    - new interface for fractional scaling

src/ifs/wl_surface/xdg_surface/xdg_toplevel.rs

@@ -456,8 +456,7 @@ impl ToplevelNode for XdgToplevel {
         Some(self.xdg.surface.clone())
     }
 
-    fn tl_set_workspace(self: Rc<Self>, ws: &Rc<WorkspaceNode>) {
-        self.toplevel_data.workspace.set(Some(ws.clone()));
+    fn tl_set_workspace_ext(self: Rc<Self>, ws: &Rc<WorkspaceNode>) {
         self.xdg.set_workspace(ws);
     }
 
@@ -548,12 +547,7 @@ impl XdgSurfaceExt for XdgToplevel {
             self.extents_changed();
             if let Some(workspace) = self.xdg.workspace.get() {
                 let output = workspace.output.get();
-                let bindings = output.global.bindings.borrow_mut();
-                if let Some(binding) = bindings.get(&self.xdg.surface.client.id) {
-                    for binding in binding.values() {
-                        self.xdg.surface.send_enter(binding.id);
-                    }
-                }
+                surface.set_output(&output);
             }
             // {
             //     let seats = surface.client.state.globals.lock_seats();