Make ::setCategory() consistent with the corresponding singular method,
which is ::addCategory(), not ::addCategoryLink(). Also, don't return
a value.
This renaming is in preparation for factoring out a write-only base
class from ParserOutput suitable to be used by Parsoid.
Note that OutputPage does distinguish a 'category link' from a
'category list', and there are separate OutputPage::getCategories()
and OutputPage::getCategoryLinks() methods. However, the category
map in ParserOutput isn't exactly the same as either of these:
it's actually a map (or list of pairs) of category name to sort key.
Rename ParserOutput::getCategoryLinks() to ::getCategoryNames()
in order to clarify that the concept involved is not the same as
the OutputPage "category links" methods.
Code search:
https://codesearch.wmcloud.org/deployed/?q=-%3E(get%7Cset)CategoryLinks%5C(&i=nope&files=&excludeFiles=&repos=
(Note that many of the code search matches are for the methods in
OutputPage, which we are trying to disambiguate here.)
Bug: T287216
Change-Id: Idb383d3d9ef7b76f8a0208a057a3cb8c639465c9
