Allow for emergency contacts
Calls should be able to treat some contacts as user configurable "emergency contacts". Those would then be added to the list of available emergency numbers whenever there's a call capable modem (e.g. not when the sim is locked).
Long term we want to fetch those via folks so they can be maintained in gnome-contacts and and do some flagging there. Short term just fetching information from
~/.config/phosh/EmergencyInfo.keyfile could be a viable option as Phosh's emergency contact plugin gets them from there anyway.