change(ble): Add Time Update service

This adds BLE a characteristic which allows to set the current time. The time is set in milliseconds since 1.1.1970 as 64 bit value.

Originally in https://git.card10.badge.events.ccc.de/card10/firmware/merge_requests/102 but rebased here.

Looks good to me! Thanks for keeping our codebase clean.

However, I'm only a bot - so a human will still have to approve this request.

merged

mentioned in merge request !102 (closed)