Push: Check that the event type is enabled before scheduling job
Push: Check that the event type is enabled before scheduling job

It is the notifier implementation's responsibility to check the user's
notification preferences before sending a notification. This adds the
check.

Change-Id: I4b7fd7ea444f5a6db6d79fadb48a440d4fdf0ac9

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