Add front-office 'View on front' action for Everblock pages

[CySSoO]

Motivation

• Provide a quick admin action to open an Everblock guide page in the front office from the pages list when the page is active.
• Match existing behavior in other Everblock admin controllers that expose a viewfront action for front links.
• Avoid showing the action for inactive pages or when the page has no link_rewrite to prevent broken links.

Description

• Added a viewfront row action in AdminEverBlockPageController::renderList to show the new button in the list.
• Implemented displayViewfrontLink($token, $id, $name = null) in controllers/admin/AdminEverBlockPageController.php which loads the page, returns empty when invalid/inactive or missing link_rewrite, and builds the front URL via getModuleLink.
• The method renders an HTML button link with an icon, target="_blank", uses Tools::safeOutput for safety, and localizes the title with $this->l.

Testing

• No automated tests were run for this change.

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Codex Task