Use Drupal.theme() to render the allday checkbox

Problem/Motivation

Smart date creates a generic checkbox for the All day element.

It can look slightly off, or broken on certain themes if the necessary classes aren't set.

Drupal has an API for this, see Claro, so we should make use of it where possible.

Steps to reproduce

Have a theme that has a custom checkbox theme in JS.

The generated checkbox needs to use the theme's checkbox template.

Proposed resolution

The generated All day checkbox should reuse the theme template in JS.

Remaining tasks

Provide MR.

User interface changes

Checkboxes are closer to the expected theme styles and can be themed accordingly.

API changes

N/A

Data model changes

N/A