Add a settings backup & restore mechanism

[serovar]

I think it would be very convenient, especially for users who manually select resolvers and routes and that setup Simple DnsCrypt on multiple devices.

[slyphnier]

there is backup and restore function build on it, but intended for keeping the config upon updating (in setting you should find "Backup and restore dnscrypt configuration on update")

while its not convenient as save-as-file then load-file but i think you can copy those saved-config files in installation folder or user-application-folder (i havent check the exact location, but i believe within those 2)

[rescenic]

Just backup/copy your dnscrypt-proxy.toml file and restore/paste it back whenever you want.. https://github.com/bitbeans/SimpleDnsCrypt/issues/537#issuecomment-817123129