Fully remove the redrawSurface API

This is a tiny addon from the recent gtk-ng work. We've moved redraw
requests into the apprt action system (the `render` action). I waited
until I had my macOS machine to verify that this fix could work. We can
now remove this completely.

We can probably remove the redraw inspector API too at some point but
I'm not there yet with the GTK backend so I'll just wait on it.

src/apprt/embedded.zig

@@ -249,12 +249,6 @@ pub const App = struct {
         self.core_app.alloc.destroy(surface);
     }
 
-    pub fn redrawSurface(self: *App, surface: *Surface) void {
-        _ = self;
-        _ = surface;
-        // No-op, we use a threaded interface so we're constantly drawing.
-    }
-
     pub fn redrawInspector(self: *App, surface: *Surface) void {
         _ = self;
         surface.queueInspectorRender();