title	issue
Implement cms buy box element in Storefront	NEXT-11747

Core

Added Shopware\Core\Content\Product\Cms\BuyBoxCmsElementResolver to resolve data for buy-box cms element.
Added Shopware\Core\Content\Cms\SalesChannel\Struct\BuyBoxStruct.php to handle data for buy-box cms element.

Storefront

Added method switchBuyBoxVariant in Storefront\Controller\CmsController.php to handle product variant switch for buy box element
Changed delivery information template in Shopware\Storefront\Resources\views\storefront\component\delivery-information.html.twig
Added cms buybox element template in Shopware\Storefront\Resources\views\storefront\element\cms-element-buy-box.html.twig
Added buy widget template in Shopware\Storefront\Resources\views\storefront\component\buy-widget\buy-widget.html.twig
Added buy widget form template in Shopware\Storefront\Resources\views\storefront\component\buy-widget\buy-widget-form.html.twig
Added buy widget price template in Shopware\Storefront\Resources\views\storefront\component\buy-widget\buy-widget-price.html.twig
Added buy widget configurator template in Shopware\Storefront\Resources\views\storefront\component\buy-widget\configurator.html.twig
Added new BuyBoxPlugin Resources/app/storefront/src/plugin/buy-box/buy-box.plugin.js to handle logic for buy box element
Changed VariantSwitchPlugin Resources/app/storefront/src/plugin/variant-switch/variant-switch.plugin.js to handle product variant switch for buy box element