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