wayland/xdg-toplevel-drag: Disable show/hide effects

This disables the visibility change effects for the dragged window,
which makes it feel a bit smoother.

TODO: Double-check whether this is indeed desirable. Note: ChromeOS imp
does this and Chromium-X11 used to do this at client side.

Status:

- [x] Basic window drag triggering
- [x] Exclude the dragged window from event targets
- [x] Event forwarding (window drag vs wayland grabs)
- [x] Offset calc relative to toplevel geometry
- [x] Attach already mapped windows
- [x] Properly support not-yet-mapped windows
- [x] Disable visibility change animations
- [ ] Dnd events stream adaptations

Signed-off-by: Nick Diego Yamane <nickdiego@igalia.com>
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4107>

src/core/window.c

@@ -2473,6 +2473,9 @@ meta_window_show (MetaWindow *window)
           break;
         }
 
+      if (meta_window_is_tied_to_drag (window))
+        effect = META_COMP_EFFECT_NONE;
+
       meta_compositor_show_window (window->display->compositor,
                                    window, effect);
       window->pending_compositor_effect = META_COMP_EFFECT_NONE;
@@ -2560,6 +2563,9 @@ meta_window_hide (MetaWindow *window)
           break;
         }
 
+      if (meta_window_is_tied_to_drag (window))
+        effect = META_COMP_EFFECT_NONE;
+
       meta_compositor_hide_window (window->display->compositor, window, effect);
       window->pending_compositor_effect = META_COMP_EFFECT_NONE;
     }