Allow users to enter phone number during setup / configuration

[CoryFoy]

As part of the CoT user message we can include a phone numbers which allows ATAK/iTAK users to tap on the user and have quick access to call them. Apple doesn't support querying for the devices number (which would be problematic on tablets, phones without sims, or phones with multi-sim) but we can add a setting for the users phone number and expose it during the setup process and in the settings pane

[miniwg]

To add the TAK server and ATAK will support numbers in international format - ie: +12345678900
So input validation should allow '+ 0-9'
The CoT message field used for the functionality is in the 'contact' section: <contact callsign="Test" phone="+12345678900" />