[5.x] Allow config values to be used in forms (#11403)

Co-authored-by: Jason Varga <jason@pixelfear.com>

Author: FrittenKeeZ

src/Forms/Form.php

@@ -17,6 +17,7 @@
 use Statamic\Events\FormDeleting;
 use Statamic\Events\FormSaved;
 use Statamic\Events\FormSaving;
+use Statamic\Facades\Antlers;
 use Statamic\Facades\Blueprint;
 use Statamic\Facades\File;
 use Statamic\Facades\Form as FormFacade;
@@ -268,6 +269,12 @@ public function delete()
     public function hydrate()
     {
         $contents = YAML::parse(File::get($this->path()));
+        $variables = ['config' => config()->all()];
+        array_walk_recursive($contents, function (&$value) use ($variables) {
+            if (is_string($value)) {
+                $value = (string) Antlers::parse($value, $variables);
+            }
+        });
 
         $methods = [
             'title',