Based on reports here https://meta.discourse.org/t/improved-bookmarks-with-reminders/144542
* Because the `userHasTimezone` property was computed and we were checking on an (essentially) global object, ember was not aware that the user timezone had changed because it changed in a different place. instead set the timezone as internal state for the modal on show and base the computed property off of that so it mutates correctly
* The tap-tile components were in the admin folder completely unnecessarily, move them out into the main discourse folder otherwise noone else can use the new bookmarks (icon + text is missing)
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