New when() helper. (#52665)

* feat(blade): New @when directive.

* StyleCI

* fix: move to compilesConditionals + remove default expression

* fix: styleCI

* fix: when() returns the value, rather than echoing it.

* fix: Remove @throws tags

* fix: styleCI

* fix: escaping on by default

* fix: remove blade directive and adds tests for when helper

* StyleCI

* remove default, add more tests.

* Remove return type

* StyleCI

* Update helpers.php

* move function

---------

Co-authored-by: Taylor Otwell <taylor@laravel.com>

Author: danmatthews

helpers.php

@@ -236,3 +236,21 @@ function value($value, ...$args)
         return $value instanceof Closure ? $value(...$args) : $value;
     }
 }
+
+if (! function_exists('when')) {
+    /**
+     * Output a value if the given condition is true.
+     *
+     * @param  mixed  $condition
+     * @param  \Closure|mixed  $output
+     * @return mixed
+     */
+    function when($condition, $output)
+    {
+        if ($condition) {
+            return value($output);
+        }
+
+        return null;
+    }
+}