(core) Form kanban tasks

Summary:
- Open all links in a new tab
- Excluding not filled columns (to fix trigger formulas)
- Fixed Ref/RefList submission
- Removing redundant type definitions for Box
- Adding header menu item
- Default empty values in select control

Test Plan: Updated

Reviewers: georgegevoian

Reviewed By: georgegevoian

Differential Revision: https://phab.getgrist.com/D4166

app/server/lib/DocApi.ts

@@ -166,6 +166,7 @@ handlebars.registerHelper('dompurify', (html: string) => {
   return new handlebars.SafeString(`
     <script data-html="${handlebars.escapeExpression(html)}">
       document.write(DOMPurify.sanitize(document.currentScript.getAttribute('data-html')));
+      document.currentScript.remove(); // remove the script tag so it is easier to inspect the DOM
     </script>
   `);
 });