window-slot: Don't access the tab view

The slot accesses the window's tab view to change the selected tab.

This is a layer violation, which is both completely unnecessary and
is getting in the way of reusing the slot widget in a tabs-less
window (such as the upcoming FileChooser window).

So, have NautilusWindow manage the selected tab directly. This is
one less NautilusWindow method being called by NautilusWindowSlot.

Part of https://gitlab.gnome.org/GNOME/nautilus/-/work_items/3402

src/nautilus-window-slot.c

@@ -3240,16 +3240,8 @@ nautilus_window_slot_set_active (NautilusWindowSlot *self,
 
         if (active)
         {
-            AdwTabView *tab_view;
-            AdwTabPage *page;
-
             window = self->window;
 
-            tab_view = nautilus_window_get_tab_view (window);
-            page = adw_tab_view_get_page (tab_view, GTK_WIDGET (self));
-
-            adw_tab_view_set_selected_page (tab_view, page);
-
             /* sync window to new slot */
             nautilus_window_sync_allow_stop (window, self);
             nautilus_window_sync_title (window, self);

src/nautilus-window.c

@@ -897,14 +897,6 @@ nautilus_window_sync_allow_stop (NautilusWindow     *window,
     }
 }
 
-AdwTabView *
-nautilus_window_get_tab_view (NautilusWindow *window)
-{
-    g_return_val_if_fail (NAUTILUS_IS_WINDOW (window), NULL);
-
-    return window->tab_view;
-}
-
 /* Callback used when the places sidebar changes location; we need to change the displayed folder */
 static void
 open_location_cb (NautilusWindow             *window,
@@ -2013,6 +2005,10 @@ nautilus_window_set_active_slot (NautilusWindow     *window,
     /* make new slot active, if it exists */
     if (new_slot)
     {
+        AdwTabPage *page = adw_tab_view_get_page (window->tab_view,
+                                                  GTK_WIDGET (new_slot));
+        adw_tab_view_set_selected_page (window->tab_view, page);
+
         /* inform slot & view */
         nautilus_window_slot_set_active (new_slot, TRUE);
 

src/nautilus-window.h

@@ -85,8 +85,6 @@ void                 nautilus_window_sync_location_widgets (NautilusWindow *wind
 
 void nautilus_window_reset_menus (NautilusWindow *window);
 
-AdwTabView * nautilus_window_get_tab_view (NautilusWindow *window);
-
 void     nautilus_window_show_about_dialog    (NautilusWindow *window);
 
 /* sync window GUI with current slot. Used when changing slots,