Dialogs: Show more (supported) protocols in "New Network Connection" dialog

Use a static subset list from
https://api.kde.org/frameworks/kio/html/kurlnavigatorprotocolcombo_8cpp_source.html
plus "ftps" in case it will be suppported in KF5.

FIXED: [ 272108 ] Support for more KIO slaves in Network Connection
BUG: 272108