Add PLURAL support to push-tab-*-override

<https://translatewiki.net/wiki/Thread:Support/About_MediaWiki:Push-tab-files-override/en>
<https://translatewiki.net/wiki/Thread:Support/About_MediaWiki:Push-tab-template-override/en>

Change-Id: Iafda0f83621b21fa8eceb4aa0fe49dd120c6fa7e
Merge "Add PLURAL support to push-tab-*-override"