view: arrange on unmap if fullscreened from layout

We don't rearrange the layout on fullscreening a view that is part of
the layout since the fullscreened view hides the layout. This means that
if a non-floating fullscreen view is closed the layout needs to be
rearranged.

river/View.zig

@@ -373,7 +373,8 @@ pub fn unmap(self: *Self) void {
 
     self.output.sendViewTags();
 
-    if (!self.current.float and !self.current.fullscreen) root.arrange();
+    // Still need to arrange if fullscreened from the layout
+    if (!self.current.float) root.arrange();
 }
 
 /// Destory the view and free the ViewStack node holding it.