datetime runner: Match timezones less restrictively

Summary:
Instead of just showing the first match, show all of the matches. So if Europe was the query, it will list several european cities instead of a random one.
Makes it much easier to find what you're looking for.

Test Plan: Used it

Reviewers: #plasma, hein

Reviewed By: #plasma, hein

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D17064