Data synchronization indication for each segment

Make it visible if data from a segment (or a run) is only available locally on the device or is synced to the CARV servers.

Could be done as a “sync ok” indication in the user interface. Or as a “not synced” indication. It could also be complemented with a “sync now” button. This button could even override a “wiFi-only sync setting, possibly after a user confirmation.