Add parameter "new" to editEntity API

* Note that this will probably break current bots!
* This also breaks some QUnit tests due to current incompatibility of wikibase.RepoApi.js. Fix will be provided in a follow-up.

Bug: 49526

Change-Id: I6cdd0039dee35892fc9ea5ed8b3b60133adb03b9
Merge "Add parameter "new" to editEntity API"