FIX: Gracefully handle DNS issued from SSRF lookup when inline oneboxing (#19631)

There is an issue where chat message processing breaks due to
unhandles `SocketError` exceptions originating in the SSRF check,
specifically in `FinalDestination::Resolver`.

This change gives `FinalDestination::SSRFDetector` a new error class
to wrap the `SocketError` in, and haves the `RetrieveTitle` class
handle that error gracefully.

lib/retrieve_title.rb

@@ -9,7 +9,7 @@ module RetrieveTitle
       max_redirects: max_redirects,
       initial_https_redirect_ignore_limit: initial_https_redirect_ignore_limit
     )
-  rescue Net::ReadTimeout
+  rescue Net::ReadTimeout, FinalDestination::SSRFDetector::LookupFailedError
     # do nothing for Net::ReadTimeout errors
   end