Use the mock HTTP request, in preparation for I1702c11928f87
Depends-On: I8ce17da7315b87b8dd0e502e601b9ac488089456
Needed-By: I1702c11928f8760bb41b41f4c7c04d7af03f62e2
Bug: T262443
Change-Id: I390856b4609635cee22253071f21ce63ff716791
Finishes the implementation of the stubbed NotificationServiceClient.
Sends push notification request messages to the endpoint configured in
the EchoPushServiceBaseUrl setting. For example, to send messages to an
instance of mediawiki/services/push-notifications running on the host
machine while running MediaWiki in Docker, add the following line to
LocalSettings.php:
$wgEchoPushServiceBaseUrl = 'http://172.17.0.1:8900/v1/message';
Bug: T252899
Change-Id: Icab7825e9080d6b1a4cfc5e12fed1da221ce4610
