Add wxART_REFRESH and wxART_STOP to GTK art provider

This provider is supposed to have all the icons that the Tango provider
has because this is the justification for turning off support for the
latter when using wxGTK, see logic for setting wxUSE_ARTPROVIDER_TANGO
in configure.in, but it didn't provide two of the recently added ones.

Do add them and also add a reminder to Tango provider code to ensure
this doesn't happen again.

Closes #22550.

src/common/arttango.cpp

@@ -196,6 +196,9 @@ wxTangoArtProvider::CreateBitmapBundle(const wxArtID& id,
         { wxART_REFRESH,            BITMAP_DATA(view_refresh)               },
         { wxART_STOP,               BITMAP_DATA(process_stop)               },
 
+        // Note: when adding elements here, try to also add the corresponding
+        //       icon to src/gtk/artgtk.cpp as the GTK art provider is supposed
+        //       to have all the icons the Tango provider has, see configure.in.
     };
 
     #undef BITMAP_DATA

src/gtk/artgtk.cpp

@@ -118,6 +118,9 @@ const wxString wxId2Gtk[] = {
     ART(wxART_FIND,             GTK_STOCK_FIND, "edit-find")
     ART(wxART_FIND_AND_REPLACE, GTK_STOCK_FIND_AND_REPLACE, "edit-find-replace")
     ART(wxART_FULL_SCREEN,      GTK_STOCK_FULLSCREEN, "view-fullscreen")
+    ART(wxART_REFRESH,          GTK_STOCK_REFRESH, "gtk-refresh")
+    ART(wxART_STOP,             GTK_STOCK_REFRESH, "gtk-stop")
+
     ART(wxART_EDIT,             "accessories-text-editor", "accessories-text-editor")
 };