Issue 482 fix event display

[mariacha]

What issue(s) does this solve?

• Issue Number: https://github.com/wri/WRIN/issues/482

What is the new behavior?

• Changes a largely-hard-coded DSField for the Add To Calendar button into a field that uses configuration options borrowed from the AddToCalendar widget.
• Creates a Calculated field that just returns whatever value is in the Date/Time field (so I can display the same field twice).

Profile requirements:

• Does deploying this change require a change to config at the site level (choose one)?
  • No config change is required.
  • Yes, and I have written an update hook to apply these config changes.
  • Yes, and I've included updating instructions to be added to the release notes. The next release will need to be a major version increase. (Only do this in special cases.)

Site-level pull requests for testing. Only merge when these PRs are approved:

Create or update any site-level pull requests following the documentation

• Flagship PR: https://github.com/wri/wriflagship/pull/1274

Checked on develop (TA to do)

• Brasil
• China
• Indonesia