Add option to disable WAN access with password only (and entry to save authorized keys)

[3v1n0]

Device Model: DGA4132

Accessing from WAN using password is at least discouraged, as per this, would be nice to have an option that:

• When you select WAN access it disables the password access
• A text area that allows to edit ~/.ssh/authorized_keys

To disable password access what I'm doing currently is just:

cat disable-root-acess.sh 
cp .ssh/authorized_keys /etc/dropbear/ -v
uci set dropbear.lan.RootPasswordAuth=0
uci set dropbear.public_lan.RootPasswordAuth=0
uci set dropbear.wan.RootPasswordAuth=0
uci set dropbear.lan.PasswordAuth=0
uci set dropbear.public_lan.PasswordAuth=0
uci set dropbear.wan.PasswordAuth=0
uci commit