DEV: Explicitly define primary_email_verified? method for managed authenticators (#19127)

We're going to change the default return value of the `primary_email_verified?` method of `Auth::ManagedAuthenticator` to false, so we need to explicitly define the method on authenticators to return true where it makes sense to do so.

Internal topic: t/82084.

lib/auth/twitter_authenticator.rb

@@ -23,4 +23,10 @@ class Auth::TwitterAuthenticator < Auth::ManagedAuthenticator
               strategy.options[:consumer_secret] = SiteSetting.twitter_consumer_secret
            }
   end
+
+  # twitter doesn't return unverfied email addresses in the API
+  # https://developer.twitter.com/en/docs/twitter-api/v1/accounts-and-users/manage-account-settings/api-reference/get-account-verify_credentials
+  def primary_email_verified?(auth_token)
+    true
+  end
 end