Add accessibility features including button and panel

- Introduced an accessibility button that toggles a panel with options.
- Implemented high contrast mode toggle functionality.
- Added CSS styles for accessibility button and panel.
- Created JavaScript to manage accessibility features and local storage for user preferences.
- Included necessary CSS and JS files in the theme's head template.

themes/InterBlue/templates/_partials/head.tpl

@@ -101,4 +101,6 @@ height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript>
 <noscript><iframe src="https://www.googletagmanager.com/ns.html?id=GTM-KF4K52D"
 height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript>
 <!-- End Google Tag Manager (noscript) -->
-{/literal}
+{/literal}
+<script type="text/javascript" src="/themes/InterBlue/assets/js/accessibility.js"></script>
+<link rel="stylesheet" href="/themes/InterBlue/assets/css/accessibility.css">