Support thank-you time on contributions

Currently, the "Set Thank-you Date on Contributions" action always sets the time to 00:00:00. One of my clients found this confusing, so I improved the action to allow setting the time (or choosing the time of the action). In addition, I converted the jCalendar widget to datepicker, since jCalendar is deprecated and not up to modern a11y standards. Finally, I renamed thank_you_radio to thank_you_date_radio to disambiguate the new options, and preserved the current behavior for existing rules.

I'm open to modifications here. You can test this pretty easily because there are a limited number of permutations and the outcomes should be clear. I'm also willing to write unit tests if there is an example CiviRulesActions test to work from!