Add new js to support tabbed accessibility in libcal hours module

Problem/Motivation

To complement changes to the custom ual_libcal_hours module, a new rivet-based javascript for tabs functionality needs to be added to this theme. See https://github.com/BluesparkLabs/IULD8/tree/develop/web/modules/custom/u...

Steps to reproduce

New feature

Proposed resolution

Add `rivet.tabs.min.js` file to themes/contrib/iu/js themes directory; add call to this file in `themes/contrib/iu/iu.libraries.yml`; and add an init to initialize the rivet js for tabs in `themes/contrib/iu/js/init.js`.

iu.libraries.yml (line 15)

global styling: 
         js:
              js/rivet.tabs.min.js

init.js (line 106)

Rivet.init();

Remaining tasks

Up-to-date rivet.tabs.min.js file can be found at IUBLibTech repo. https://github.com/IUBLibTech/Rivet-components/blob/main/dist/tabs/js/ri...

User interface changes

API changes

Data model changes