Show timezone for datetime picker

A customer was excited about the new datetime picker UI, but they weren't sure how timezones were being handled. They were surprised when the DB's system timezone was used (PDT) instead of their local timezone or UTC. They thought this made sense, but suggested making this more obvious/transparent in the UI if possible.

I'm not sure how much control we have in the datepicker widget, but wanted to pass along the customer feedback.