LibGUI: Allow double-clicking PathBreadcrumbbar buttons to edit path

When viewing a deeply nested path, there may be very little of the
PathBreadcrumbbar itself visible to double-click on. This solves that
by allowing double-clicks on its segment buttons to behave the same.
(With the caveat that it first selects the double-clicked segment.)

In order to make this work, `on_double_click` now takes the modifiers
instead of the MouseEvent. In this case we don't use it so that's fine,
but maybe we should make all mouse callbacks consistently take the
MouseEvent& as a parameter.

Userland/Libraries/LibGUI/PathBreadcrumbbar.cpp

@@ -80,7 +80,7 @@ PathBreadcrumbbar::PathBreadcrumbbar(NonnullRefPtr<GUI::TextBox> location_text_b
             on_paths_drop(m_breadcrumbbar->segment_data(segment_index), event);
     };
 
-    m_breadcrumbbar->on_doubleclick = [&](GUI::MouseEvent const&) {
+    m_breadcrumbbar->on_doubleclick = [&](auto) {
         show_location_text_box();
     };
 }