Create bot to comment in Gerrit when a wiki is created

[jhsoby]

The tool can leave comments in related Phabricator tasks when a patchdemo is created. It would be nice if it could leave comments on the patch itself in Gerrit as well.

[edg2s]

Upstream request:
https://phabricator.wikimedia.org/T332474

[hashar]

I have commented on the Phabricator task about adding the integration: https://phabricator.wikimedia.org/T332474#8708942