Detecting if UTILITY is popup (#323)

Ardour uses UTILITY atom all over the place for toplevel windows:
Plugins, Dialogs etc
However it does not provide any MOTIF_HINTS at all.

WeChat however uses them for popups and also provides MOTIF_HINTS with
flags 0x2 indicating that only decorations are active. MaterialMaker
also follows what WeChat is doing for right click menus.

This fix assigns UTILITY as popup ONLY if MOTIF_HINTS are provided and
functions are not active.

Couple of apps like Godot mark their windows
(_NET_WM_WINDOW_TYPE_UTILITY) with override_redirect which makes them
popup by default. Potentionally is_popup can be overriden in case MOTIF
functions exists with so no_function_motif would be false.

This fix prefers override_redirect in case that scenario comes up.

Closes #294

src/server/event.rs

@@ -140,7 +140,7 @@ impl Event for SurfaceEvents {
                 let needs_server_side_decorations = window_data
                     .attrs
                     .decorations
-                    .is_none_or(|d| d == Decorations::Server);
+                    .is_none_or(|d| d.is_serverside());
 
                 if mode == Mode::ServerSide || !needs_server_side_decorations {
                     let mut role = entity.get::<&mut SurfaceRole>().unwrap();