Instead of just the configuration variable $wgCookieWarningMoreUrl,
CookirWarning now allows also to set the link on-wiki using the interface
message MediaWiki:Cookiewarning-more-link. It also "listens" for the
MediaWiki:Cookie-policy-link interface message, which is introduced by
Cookie Policy as a first step for merging these both extensions.
Bug: T145781
Change-Id: I818008b2da6d9acd4295857e2916cd1b4637bee9