Add UTC time to selectable clocks

[Emanz93]

Is your feature request related to a problem? Please describe. I work in a scientific environment, spacecraft operations in particular, where we work in UTC. It is handy to have this time on our clock app especially when travelling in countries with other timezones.

Describe the solution you'd like It would be great to have the possibility to add UTC to the list of clocks in the Clock section. Currently it is possible only to search for cities.

Describe alternatives you've considered As a workaround, one can add Rejkiavik as they are basically in UTC and don't have summer/winter time.