Add new Wikidata messages for "other projects" sidebar links and for new magic word

preemptively adding Wikiquote messages also, since it is planned
to add language links there on April 8.

Change-Id: I23a75212aea5fc5ccfd30e78faf3d2feb4291755
(cherry picked from commit 90e06429c45a799e2b71ce2d0733f2702a6da0ce)