certificate handling after 10years

Auto reconfiguration of own certificate:

currently: if kdeconncectd loads its certificate and its expired or not effective yet it generates a new certificate

previously: if kdeconncectd loads its certificate and its expired or not effective yet it continues having the same certificate This brings forth an issue: Other devices would refuse to connect to a device with an expired or non-effective certificate.

Auto-delete of orphan certificates:

currently: Devices in kdeconnectd's devicelist that have illegal ssl certificates (expired, not effective yet, empty) get automatically deleted from the devicelist

previously: they would just exist forever until the user deletes them

A year does not have 356 days:

currently: int a_year_in_seconds = 365 * 24 * 60 * 60;

previously: int a_year_in_seconds = 356 * 24 * 60 * 60;