init header components

src/app/browser/header/tray/tab.rs

@@ -0,0 +1,18 @@
+use gtk::Button;
+
+pub fn new() -> Button
+{
+    let tab = Button::builder()
+
+        .icon_name(
+            "tab-new-symbolic"
+        )
+
+        .tooltip_text(
+            "New tab"
+        )
+
+        .build();
+
+    return tab;
+}