Add a test to validate $wgEchoNotifications
Add a test to validate $wgEchoNotifications

Change-Id: I7c9f76f4222f692a2babf47618b869f4c963499f

wikimedia/mediawiki-extensions-Echo,wikimedia/mediawiki-extensions-Echo,wikimedia/mediawiki-extensions-Echo,wikimedia/mediawiki-extensions-Echo