use canonical module subfolder tree

src/app/browser/header/tray.rs

@@ -1,20 +0,0 @@
-#[path = "tray/menu.rs"]
-mod menu;
-#[path = "tray/tab.rs"]
-mod tab;
-
-use gtk::prelude::BoxExt;
-use gtk::Box;
-
-pub fn new() -> Box {
-    let tray = Box::builder()
-        .orientation(gtk::Orientation::Horizontal)
-        .spacing(8)
-        .build();
-
-    // Compose childs
-    tray.append(&menu::new());
-    tray.append(&tab::new());
-
-    tray
-}