The forum advanced search form needs some styling

Test in Boost and Clean (Moodle 3.6) as well as Boost and Classic (Moodle 3.7 and master). In a course in which you have a forum, go to that forum. To access to the advanced forum's search, in breadcrumb navigation, press the "Search forums" button without having insert a search term. Verify the date chooser looks like in other Moodle UI elements, e.g. the assignment setup interface. Verify the "These words can appear anywhere in the post" label does horizontally align to its input field. For Clean (Moodle 3.6),  verify the user interface looks the same as without this patch.