Fix uses of addPart to make them async friendly

Problem:

Adding or moving templates or content resulted in the incorrect item
being selected.

Diagnosis:

Although recently we solved a few issues by making addPart async, it
caused some other issues where callers of addPart were assuming
otherwise

Solution:

Return a promise from addPart which is resolved after the part is
actually added and setup callers to use the promise when needed

Changes:

ve.ui.MWTransclusionDialog.js
* Use promises to auto-select new or moved parts

ve.dm.MWTranclusionModel.js
* Make addPart return a promise
* Resolve promise when queue is processed
* Automatically remove existing items before adding them in different
  locations at the time of processing the queue we don't yield between
  removing and adding

Change-Id: Ie43c5b89ca4ed34d5f797714e19c9a7e1824cdec
Merge "Fix uses of addPart to make them async friendly"