Revert "Revert "[MediaWikiChat] Register extension""

Issues with duplicate keys

This reverts commit 83c65a87b164d135bd999d2530eb23a0a3400ad3.

Change-Id: I5620de1b615c24415f48c77ef76e20fdf2e4ffe4
Merge "Revert "Revert "[MediaWikiChat] Register extension"""