[Linux] IWD config file created in current directory rather than `/var/lib/iwd/`

I use NetworkManager with IWD and when I run the eduroam CAT tool with the `--iwd_conf` option, the `eduroam.8021x` file is created in the current working directory rather than the correct place (`/var/lib/iwd/`). This means eduroam doesn't work until I manually copy this file to the correct location.

I think this was fixed in #292 but that PR was closed for some reason.