Issue 323: Event Page 'Add to Calendar' feature

[YolineB]

PR Overview

Implement 'Add to Calendar' option in Event Page with https://github.com/add2cal/add-to-calendar-button

Type of contribution

• [x] Code
• [ ] Documentation

Reference: Issue or Pull Request (PR)

• [x] Towards #323

Description of Changes

<-- Brief description of the changes you made, files you touched, etc -->

Before and After for UI Updates

Before:

After:

Calendar shots:

For PR Reviewer

• [ ] Does this file change the yarn.lock, package.json or package-lock.json file? If so, why?
• [ ] If this pr contains mobile and desktop changes, did you test on IphoneXr and desktop views?
• [ ] Does this file match the related tickets linked figma file, or does it pass the visual smell test?
• [ ] If this file contains javascript, does the javascript pass the smell test?
• [ ] If you don't feel super confident in your review, did you assign someone more senior to double check?