API: Split list=deletedrevs into prop=deletedrevisions and list=alldeletedrevisions

API: Split list=deletedrevs into prop=deletedrevisions and list=alldeletedrevisions

list=deletedrevs has always been an odd one: it pretends to be a prop
module sometimes in taking titles from ApiPageSet, but when the pageset
supplies no titles it acts like a list module. This causes problems
such as bug 71389, and makes the whole thing unnecessarily confusing.

The solution is to split the "prop" and "list" aspects into separate
modules: prop=deletedrevisions when input should come from ApiPageSet
and list=alldeletedrevisions when not.

At the same time, let's take advantage of the situation to clear up some
other bugs. And let's share the revision-formatting code with
ApiQueryRevisions instead of partially reimplementing it.

Bug: 23489
Bug: 27193
Bug: 44190
Bug: 71396
Bug: 71389
Change-Id: I3e960d5c655bc57885d6d4ee227e67104808add7