Add a Toolbars settings page: icon size, text with icons, lock

A new page in Configurer QElectroTech, "Barres d'outils", sets for
every window (folio editor, element editor, title block editor):
- the icon size: default, 16, 24, 32 or 48 px
- the buttons: icon only, text beside the icon, or text under it
- locking the toolbars so they can't be dragged out of place

OK applies it to the open windows at once. The defaults are Qt's
own, and a default value removes its key, so nothing changes for
anyone who never opens the page. A toolbar inside a panel is left
alone; only the window's own toolbars are locked.

New test tst_toolbarsettings: defaults change nothing, saved values
reach every toolbar of an open window, back to defaults removes the
keys.

Third stage of discussion #1319.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

sources/titleblock/qettemplateeditor.cpp

@@ -27,6 +27,7 @@
 #include "templatelocationsaver.h"
 #include "templatelogomanager.h"
 #include "templateview.h"
+#include "../toolbarsettings.h"
 
 /**
 	@param parent parent QWidget of this window
@@ -46,6 +47,7 @@ QETTitleBlockTemplateEditor::QETTitleBlockTemplateEditor(QWidget *parent) :
 	initActions();
 	initMenus();
 	initToolbars();
+	ToolbarSettings::applyTo(this);
 	readSettings();
 }