Add site's default time zone to the default values list

Sounds like a useful feature, were you interested in contributing as a merge request, or just putting it out there as a suggestion?

Since time zone is configurable at both the site and (potentially) user level, folks might want to allow the default value to be set to either the site's default time zone or the current user's time zone.

Here's a patch that does this with two checkboxes. A literal default value being set will override anything else, so I disable the new checkboxes if the "set default value" checkbox is checked. If both site default and user time zone checkboxes are checked, and the user doesn't have a time zone configured, it will fall back to the site default time zone.

Add tests

Went ahead and committed this so folks can test it out. @goodboy let me know if you're able to test out the dev branch.

Automatically closed - issue fixed for 2 weeks with no activity.