(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/client/models/features.ts

@@ -33,7 +33,3 @@ export function PERMITTED_CUSTOM_WIDGETS(): Observable<string[]> {
   }
   return G.window.PERMITTED_CUSTOM_WIDGETS;
 }
-
-export function GRIST_FORMS_FEATURE() {
-  return Boolean(getGristConfig().experimentalPlugins);
-}