chore: upgrade jQuery UI from 1.12.1 to 1.14.2

- Remove legacy jQuery UI 1.12.1 CSS, JS, and image assets, including the Smoothness theme.
- Add jquery-ui.1.14.2.min.js and metadata.json to the 1.14.2 directory.
- Update CSS and template files (Web/css/librebooking.css, Web/css/schedule.css, tpl/globalheader.tpl) to reference the new version.
- Reduce the need for jQuery Migrate to handle legacy code.

Author: labmecanicatec