Add Simple XML Sitemap defaults for Event content type

Working on it.

Hi,
Created an MR to add Simple XML Sitemap defaults for Event content type.
It successfully adds 'Events' to be included in /admin/config/search/simplesitemap/entities.

Please review.

This appears to be failing tests for legitimate reasons: https://git.drupalcode.org/issue/drupal_cms-3494066/-/jobs/3740413#L100

The tests appear to be passing now.

Please review.

Assigning to Jim for input.

The sitemap is also part of our SEO offerings, rather than any one content type, so switching track.