Work items - Use modal creation form from group issues list

Add the modal creation form on the group issues list (powered by the work items list)

• When a user clicks "New issue" from the /issues list page, they should see the creation form in a modal.
  • On creation, a toast shows the success message and a link to the detail page.
• When a user selects "Open in a new tab" on the "New issue" button, they should see the creation form in a full page (in a new tab).
• Ensure that "new item" button also exists in CE
• Issue creation flow mirrors Epic creation.

🎨 Design flow can be seen here