Fixing the output of the fundraiser_submit_message text and padlock icon

Fixing the output of the fundraiser_submit_message text and padlock icon in `fundraiser_form_alter()`.

Webform 6.x-3.0-beta2 changed how the `submit` form element is added to `$form` array. It is now inside `$form['actions']` instead of being set directly on `$form`. Previously, in `fundraiser_form_alter()`, the code attempted to add it to a (nonexistent) `$form['submit']` form element.