lib: Add nl2br view helper

refs #10603

library/Icinga/Web/View/helpers/string.php

@@ -6,3 +6,7 @@ use Icinga\Util\String;
 $this->addHelperFunction('ellipsis', function ($string, $maxLength, $ellipsis = '...') {
     return String::ellipsis($string, $maxLength, $ellipsis);
 });
+
+$this->addHelperFunction('nl2br', function ($string) {
+   return str_replace(array('\r\n', '\r', '\n'), '<br>', $string);
+});