Send a cookie with IP/IP-Range blocks when blocking logged-out users

Send a cookie with IP/IP-Range blocks when blocking logged-out users

A cookie will be set when ip users try to edit and their IP has been
blocked or if they try to create an account and the block prevents
account creation

This feature is disabled by default and can be enabled by
setting the new $wgCookieSetOnIpBlock config variable to true.

Note: this is meant to discourage vandals that try to avoid blocks by
switching their ip address while editing anonymously.

Bug: T152462
Change-Id: I0b78a5e174bcd882edea39e868a08f9a347f5aba