Use ChangeOps to generate edit summaries in API modules

* wbsetlabel, wbsetdescription, wbsetaliases and wbsetsitelink
  are now using ChangeOps
* edit summaries are updated when ChangeOps get applied

Handling of summaries of multiple ChangeOps in one API request
will be done in a followup.

Change-Id: I44c407a708b5322fdaa7adf14ff20d5561ab67c0
Merge "Use ChangeOps to generate edit summaries in API modules"