Allow to configure httplug-ssrf-plugin

[mudkipme]

I'm using wallabag and I had found wallabag couldn't download any webpages due to my network environment.

The network for my home server is configured to use a tunnel and its local DNS server responding every DNS request in 198.18.0.0/16. That kind of tools is popular in some regions.

I have figured out that it is because j0k3r/httplug-ssrf-plugin blacklisted non-public IPv4 CIDRs. While it is possible to override the default options of ServerSideRequestForgeryProtectionPlugin to allow some IP ranges, it is not exposed to GrabyConfig.

My current fix is below but it's not ideal.

sed -i '/198.18.0.0/d' /var/www/wallabag/vendor/j0k3r/httplug-ssrf-plugin/src/Options.php