Date & Time Format settings independent from display language

[ZergerZ]

Description of the feature

There is currently no way to set different clock format (Ex: 12 to 24 hour) rather than to change the display language.

It might be useful feature of the operating system to be able to change this via GUI

forum topic as reference:
https://forums.ubports.com/topic/1646/change-clock-to-24-hour-format-16-04-ota-4

[Danfro]

duplicate of #729

[mateosalta]

this might have some relevant work https://code.launchpad.net/~attente/ubuntu-system-settings/1392699/+merge/296271

[Flohack74]

Closed in favour of #729