avoid plain password in configuration file.

[Justin]

Hello

I configured openconnect client with certificate auth, the cert was
protected with password, i have to set key-password="password_of_cert"
in configuration files to make it work.

I noticed there is a `key-password-from-fsid` option, but how do i
make use of it? I have   generated a "fsid" by running `gstat
--file-system --printf=%i\\n ~/config/openconnect/ca-cert.pem`, but i
don't know where to activate it.

thanks for your help.

Regards
Justin He